Chapter Text
It was hot. Unbearably so. But it was a small price to pay. He’d see him again. He’d get to duel again. If it wasn’t with him, there was no reason for him to go out of his way like that. He reached the castle. The big doors were probably supposed to be daunting, but he had already looked death in the face and laughed. He entered the castle.
“Kaiba.”
His voice was smooth, as always. The figure on the throne greeted him with a smile. Seto didn’t hesitate. He activated his duel disk.
“I have found you.”
The pharaoh stood.
“That you have.” Plates of stone rose from the ground next to him. “Shall we throw a coin?”
“No need. I will go first.”
“Of course.”
“I end my battle phase. Now I set a trap card and end my turn.”
“It’s my turn. I draw.” Atem drew from the duel disk that had formed around his arm. “Say Kaiba. I never noticed you were an omega.”
“Of course not. Yugi’s body isn’t exactly sensitive to these things.”
“Just because he’s an omega himself? I think other omegas can still recognise each other.”
Seto scoffed, handwaving the argument away. “His nose couldn’t even pick up Mai and she was an obvious case.”
“Mai is an omega?”
“Alpha.”
“Of course.”
“Anyway, you can’t rely on Mutou’s nose. Everyone’s a beta to him until he asks.”
“I see.” Atem set a card. “Well now that I’m back in my own body, I can recognise your scent as an omega’s just fine. It’s rather strong, actually.”
Seto frowned. “It’s not supposed to be strong.”
“I could smell you from my throne as soon as you entered the room.”
“The distance wasn’t that great.”
“Yes it was.”
Blue Eyes huffed and sat down, noticing the duel would take a while. Kuriboh floated towards her and lied down on her head.
“Well, I’ve been sweating an awful lot. Maybe if it wasn’t so hot here, you wouldn’t have smelled me.”
“You’re just not used to the heat. It’ll get better with some time.” Atem rested his hands on his hips. “You could take off the coat for starters.”
Seto hesitated. Technically, the coat was more fashion than anything else. He supposed he could take it off. The coat landed on the floor next to him. Atem covered his nose.
“What?” He snapped.
“It’s gotten a lot stronger. The coat must have covered you well.”
“That’s why I wear it.”
“I see.” Atem seemed to struggle to focus. His eyes flitted around the room, then back to Seto, glancing from one body part to the next. “Well… want to take a cooling bath first then? So you can concentrate on playing after.”
That did sound nice. However, it wasn’t Seto’s style to just pause a duel like that. “Later.”
“I’m asking you to please take one.”
“What?”
“Your scent’s too strong. I can’t concentrate.”
Seto threw his hands up. “Your fucking country is too hot. I can’t concentrate either.”
“So, a bath would solve both problems.”
“I’m not pausing the duel for such arbitrary reasons.”
“Kaiba.” Atem was gritting his teeth. “Take. A. Bath.”
Seto clicked his tongue and with two long steps, he was up in Atem’s personal space and staring him down. “Are you trying to make fun of me?”
“I’m not-” Atem took a step back and gasped for air like he was being suffocated. “I’m taking you seriously! That’s why I’m offering!” A shudder ran through him. “Honestly, you smell stronger than Mana when she’s in heat!”
A pause.
“.... are you-”
“I’m not!” Seto let out a huff. “It’s just your stupidly hot country and its stupidly hot sun!”
“No, I don’t think so.” Atem took another step back. “I’ve smelt an omega in heat exactly once before but I think I should be able to recognise the difference between ‘strong smell because it’s hot’ and ‘strong smell because of heat’.”
“That’s ridiculous. I’m not even due for one.” Or at least he thought so. He wasn’t sure. Taking suppressants on and off made him unsure what his actual cycle was. But his last heat hadn’t been that long ago. There was no way his next would come that soon. “I’m telling you, you’re wrong.”
“Fine, then you just need a bath, right? And then you’ll smell normal again and we can put this stupid arguement behind us.”
“I’m not interrupting the duel!”
“Just give up already!” Atem was close to him again, grabbing a fistful of his shirt and pulling him down. He smelt divine. Seto pushed that thought aside. “Take the damn bath and I’ll duel you until you pass out!”
“And I’m telling you-!” Seto stopped mid-sentence. His pants were wet. Fuck . Fuck, fuck, fuck . He was struggling to breathe. “Let go.”
“What?” Atem was so surprised he almost did.
“Let go.” Seto repeated, voice closer to a growl than anything else. When Atem didn’t comply immediately, he ripped his shirt out of his hand. He staggered a few steps back. “We’ll finish the duel.”
Concern made its way onto Atem’s face. He took a step in his direction, hand outstretched. “Kaiba, are you-”
“Don’t get any closer!” Seto barked. “We’ll finish the duel.” He repeated, stubbornly.
“Kaiba.” Atem let his hand sink, but kept coming closer. Seto kept stepping back until there was only the wall behind him. “Kaiba, you’re clearly not alright. Do you want to rest in a room?”
A whine made its way out of Seto’s throat. Atem was so close. Too close. Come closer, come closer, come closer, come-
“Kaiba?”
Seto swallowed dryly. It seemed like all the moisture in his body was collecting in his pants. “Pharaoh….”
“Let’s get you out of here.” Atem took him by his wrist. His skin seemed to burn where his hand made contact. “You’re clearly not feeling well.” Seto wanted to protest. To say he’d rather finish the duel. Instead, he stumbled over his discarded coat. “See? We can duel when you’re feeling better. I don’t care what it is, the hot weather, fever, heat, whatever, we’re not duelling when you’re like this.”
Seto snatched his hand out of Atem’s grip. “Leave me be.” He leaned against the throne. Convenient. He felt like sitting. Or rather, he didn’t feel like standing. More than anything, he wanted to lay down. His clothes felt too heavy. His turtleneck was scratching at his throat uncomfortably.
“For Ra’s sake.” Atem turned back to him. “You can’t even stand properly, yet you want to duel like this?”
“Go away.” Come closer.
Atem gestured towards the room. “The monsters aren’t even here anymore. Everyone but you sees this duel as paused.”
True, Seto could see out of the corner of his eye that the throne room was empty. He took a deep breath. Steady. He let the breath out. Good. Ignore the urge to strip. Ignore the sweat dripping down his back. Ignore the uncomfortable wetness in his pants. Ignore the empty feeling inside him. Ignore how good Atem smelt. Sit down behind the throne. Soak in the cool shade. “My coat.”
“I’ll get it for you.”
That gave him some time. Deactivate his duel disk. Atem’s seemed to have already vanished. He needed to gather himself. Leave. Get back to the pod. Find his way back home. Take suppressants. Come back again another day. He couldn’t stay here, no matter what. Not with Atem here.
“I’ve got your coat.”
“Thanks.” His voice was rough. Atem held his coat out to him. So close. Too close. Not close enough. Seto reached out to take it, but his fingers wrapped themselves around Atem’s forearm instead and with a pull, he was on the floor next to him.
“Kaiba?” Atem sounded nervous, but at the same time, something else sounded within his voice.
“ ‘tem…” Seto groaned. A hand reached out to him. Caressing his cheek. He gripped it strongly. The next moment, Atem was lying across his lap.
“Kaiba, that’s-” Atem clambered to get up, brushing against his crotch in the process. He stilled. “You are in heat.” It wasn’t a question. Seto resisted the urge to pull Atem’s hand back to where it had brushed against.
“Yes.” He dragged a hand through his hair. “Thought I was sweating because Egypt is hot. That wasn’t it.”
“Oh.” Atem’s voice was small. “So when you said-”
“That I’m not in heat I meant it, yes.” He let his head fall against the back of the throne. “I’ll go home. We’ll finish this another day.”
“Yes.” Seto glanced back at Atem. His eyes were blown wide. “That’s probably for the best.”
“Yes. So.” Seto made no movement to leave. “Before it gets any worse.”
“It can get worse?” Atem struggled to keep his eyes on his face. Part of Seto commended his self control. Another part of him wished he had a little less of it.
“Oh, this is just the prelude.” Seto didn’t feel like explaining how, when he decided to skip suppressants, he’d be tied to his room, changing sheets several times a day, how he’d only be able to sleep after cumming three times in a row, how Mokuba was the only one able to come near him, because they were related and he was the only person Seto wouldn’t jump.
“That’s…. bad. For you, I mean.”
“Yes.” Get up. Leave. It should be so easy. So why wasn’t he doing it? He could hear Atem breathe. It sounded as struggling as his own breath. “Right, I’ll-” He shifted. Something squelched .He stopped his movement, horrified. “You didn’t hear that.”
“I didn’t hear that.” Atem’s eyes were fixed on some point behind Seto. Seto made another attempt to move, but his clothes had become too uncomfortable to bear. Any movement would shift them uncomfortably, they felt too tight, too constricting, his shirt was too soft, his pants too rough, everything felt heavy. Seto sat back down and undid the buckles on his arms. The duel disk came off. His arm braces. Better. Not by much, but better. He reached for his legs. Better. He didn’t care that he would have to carry all that back to the pod. Anything not on his body was better than anything still on his body. It still wasn’t enough. He reached for the hem of his shirt. A dark hand on his own stopped him.
“Don’t.” Atem’s voice sounded incredibly soft. “I’m not sure how much I can handle.” I don’t care, he wanted to scream back. Instead, all his senses focused on Atem’s hand on his own. It felt burning hot, but at the same time calming. And it wasn’t enough . Seto took hold of Atem’s hand again and this time, the pull closer wasn’t just an instinctual reaction. His other hand found the back of Atem’s head, his lips found his mouth. Atem provided little resistance and Seto found himself being kissed back with the same intensity. Atem’s hands landed on his shoulders and he moved to sit in Seto’s lap, pressing his body against his. Not enough. Not enough, still not enough. Seto pulled at Atem’s tunic, his cape, searched for hinges on his jewellery. He broke their kiss.
“You’re wearing too much.”
“Kaiba.” Atem stilled. Seto wanted to scream. “Are you sure? This could be just your heat making you do things you’ll regret later.”
Seto took a deep breath. He needed to find the words to convince Atem. He wanted this. “This is still the start of my heat. I can still think rationally. I wouldn’t do this with someone else.”
“I see.” Atem’s eyes shifted, thinking. “In Duelist Kingdom….. and Battle City…. you’ve always been like this.” He must have recalled something particular because thankfully, he pulled his cape off and undid his jewellery. Seto drank in his scent, now unfiltered by the lack of cloth covering Atem’s neck. Seto returned the favour by pulling off his turtleneck. Atem gasped and let his hands run down his chest. “You’re so.....” Scarred? Damaged? Muscular? “... pretty.”
Seto snorted. “Sure.” Pretty wasn’t a word he’d chose to describe himself. Handsome maybe. Pretty suited Atem so much better.
“Are you undermining my opinion of you?” Atem’s hands still rested on his pecs and he looked up at Seto with those irresistible eyes of his. “I think you’re pretty. Let me express that.”
“Fine.” Seto wasn’t one to argue compliments. Especially not when Atem was right in front of him and still not inside of him for fuck’s sake . He undid his belt and pushed down his pants, until he sat completely naked in front of Atem, oozing slick on the stone floor. Atem’s eyes followed each movement as if hypnotised. Seto spread his legs a little further so he’d get a better view. “Well?”
“It’s. Wow.” Atem’s arousal was clear as day and Seto didn’t understand why he was still just sitting there. “Just. Wow.” He put a hand over his heart, as if to calm himself. Seto began to doubt his appeal. Wouldn’t any other alpha have pounced already?
“Are you waiting for some divine intervention or is there some reason I don’t know about for why you’re taking so long?”
“Oh. Sorry.” Atem’s gaze snapped back from Seto’s body to his face. “It’s just. Aside from the one time Mana got her first heat when we were playing together, I’ve never really. You know. Seen an omega in heat. Let alone a naked one.”
A beat of silence passed.
“Are you trying to tell me you’re a virgin?”
“Yes. No. Maybe.” Atem looked off to the side. “I didn’t exactly have time for that kind of stuff.”
“That makes two of us.” Seto reached for the hem of Atem’s tunic and pulled it up to see Atem’s dick twitching beneath a loincloth. “But my patience is running out.”
Atem gave him a scandalised look. “Kaiba!”
Seto shifted so he was kneeling instead and leaned forward. “See that?” He reached between his legs and caught some of the slick between his legs. “It’s getting more the more time we waste. My body is telling me to fuck. It senses an alpha right in front of me and thinks the time has finally come. The longer we take, the more pheromones and slick it will produce. I’m sure your treasured priests can smell me from two rooms over. So just do something before I produce a puddle big enough to classify as a pond.”
“Ah. Uhm. I see.” Atem’s whole face had gone red. He too reached between Seto’s legs and caught some of the slick leaking out, his expression a mix of fascination and arousal. “It’s so thick.” Seto did his best to not just grab Atem’s hand and pull it up until he’d at least have his fingers inside him. Atem retracted his hand and instead pulled off his tunic and discarded his loincloth to the side. “Sorry. I just needed a moment to wrap my head around this.” Seto’s head went blank. Atem’s dick. He finally saw it. It was bigger than expected. Yes, it would fill him up nicely. His hole twitched at the thought of being stretched by his knot and he half just wanted to sink on Atem’s dick right then, disregarding the awkward position they would be in. Thankfully Atem sensed his patience and tanned fingers reached between his legs again, only this time not catching slick and instead brushing against his hole. Seto almost sighed in relief when one of those fingers pressed inside him and curled.
“More.” He leaned towards Atem, resting his forehead on his shoulder. “That’s nowhere near enough.” Atem complied and a second finger slipped in. Seto held onto Atem’s shoulders, bucking his hips to get more of that feeling. While his own fingers knew exactly where which spot was and how to twist to achieve maximum pleasure, having someone else do it was a different experience altogether. “More.” He demanded again. “More, more.”
“Are you sure? I just put in the second finger.”
“Exactly. Just the second. It’s not enough.”
“I don’t think that’s how it’s supposed to go.” Atem used his free hand to coax Seto’s head off of his shoulder and made him face him instead. “Look at me. You’re all tensed up.” He leaned up to kiss him and something inside Seto let go. The tension that had made him only feel Atem’s fingers left and he began to feel all of him. His sweaty skin touching his own. His breaths coming out in short, heavy bursts. His hair tickling his fingers where he was still holding onto his shoulders. All of it was Atem, not just the fingers up his ass. “There we go.” Atem wiggled his fingers and spread them apart experimentally. “You’re a lot looser now.” Seto sighed in pleasure and pushed his hips against Atem’s hand. Atem generously added a third finger and Seto shuddered.
“Good. Like that.” Seto pulled Atem closer, rubbing his dick against his chest as Atem fingered him. “I want all of you. I need more.” He heard Atem chuckle and soon after, a warm mouth was sucking at his chest, biting his nipples and leaving a wet trail of kisses across his muscles.
“Kaiba, Kaiba, Kaiba.” Atem sung. “So pretty. So sexy.” Seto shuddered, trembling and this close to an orgasm when Atem pulled his fingers out of him again. He wanted to protest when he noticed Atem spreading his cape on the floor behind the throne, and his coat on top of it. “I figured it’s better than stone.” Seto personally didn’t care, but Atem manoeuvred him on the makeshift padding with so much care that he didn’t feel like protesting anymore. “There we go.” Atem sounded satisfied with himself. “Could you maybe… uhm… hold your legs up?” Seto complied all too willingly, grabbing his thighs and pulling them back until he was nearly folded in half. Atem stared at him with badly concealed desire, looking at him from his leaking hole, over his twitching dick to his erect nipples. “Holy Ra.” He inched closer, aligning his dick with Seto’s ass and taking hold of his thighs for him. He took a deep breath, closed his eyes and in the next moment, Seto was full . He could have wept, finally, finally Atem was inside him, finally the aching inside his body stopped as he was filled with dick.
“Atem.” Seto’s voice was barely above a whimper. “So good.” Atem answered with a smile, slowly pulling out and pushing back in. Seto wanted to scream. He could feel it even more this time. It had already looked fairly big when Atem had undressed, but now that it was inside him, it felt so much bigger. He felt stretched to the brim and while his insides twitched around Atem’s dick eagerly he couldn’t help but think there was no way anything else would fit inside him.
“Is it okay if I move faster?” Seto only nodded, grasping onto the sides of the backrest of the throne for stability. Atem set a fast, but not harsh pace, jerking Seto’s body with each thrust as he buried himself deep inside him. Noises fell from Seto’s mouth that he’d deny ever making if his partner was anybody but Atem. He begged for more, for a speedier pace, for Atem to rough him up until there was no tomorrow and Atem, while still very much careful about not hurting him, complied, fingers digging into Seto’s thighs as he held on tighter, skin slapping against skin loudly as he increased his pace, calls of Seto’s name leaving his mouth whenever Seto clenched around him. “Seto, oh gods, Seto, Seto!” A shiver ran through him and he pushed himself deep, deep inside Seto, knot and all. Seto came with a cry as Atem’s knot swelled inside him, cum pooling into his stomach. They were both breathing heavily and just stared at each other for a good moment. Atem let go of Seto’s thighs. “Sorry. Did I hold them too tightly?”
“No.” Seto’s voice came out rough. It would, after all the screaming he’d done. He rolled his hips, relishing in the feeling of Atem still inside him. “It was good.” He let go of his iron grip on the backrest and used his arms to sit up. “This was… very good.”
“Even though I knotted you?” Atem looked rather concerned. “Isn’t that… rather for people who are already mates?”
Seto considered this. He couldn’t even imagine mating someone other than Atem. If it wasn’t him, he’d rather stay unmated his entire life. “I don’t care.” Atem looked like he was about to protest, so Seto pulled himself forward using Atem’s shoulders and bit harshly into his neck, enough to draw blood. “There. If you worry that much, we’re even now.” Atem touched the wound on his neck, staring at Seto in disbelief.
“But. Seto. Shouldn’t you… shouldn’t you rather do this with someone from your own world?”
Seto gave him a scrutinising look. “The same could be said about all we’ve done. The duels. The sex. The knotting.”
Atem let his hand sink and, though a bit unsure, leaned forward as well, sinking his teeth into Seto’s neck. Seto shuddered in pleasure. If he hadn’t just cum, he might have done it again.
“Good.” The smile on his lips probably resembled a smirk more than anything. “Now we’re more than even.”
Atem stared at the bite mark on Seto’s neck and swallowed dryly. “That’s one of the last things I expected happening when you arrived here.”
Seto snorted. “Be real. There’s no one you can imagine me mated to.”
Atem considered this. Considered it some more. “No, I can’t say I do.”
“See.” Seto shifted positions, going from lying down to sitting in Atem’s lap. There weren’t many positions he could take with them still connected through Atem’s knot, and this was the best option considering the situation they were in. “Either way. We have some free time now.” He reached for his coat and dug around in its inner pockets until he produced a travel sized pack of playing cards. “I suppose I can channel the king of games to something other than duel monsters once in a while.”
“I’m surprised you carry these with you.” Atem took the cards from Seto and shuffled them. Seto shrugged.
“It’s mostly to entertain children who don’t know how to play duel monsters. I come across them more often than expected.”
“I see.” Atem dealt the cards. “There’s only really space for old maid.”
Seto discarded his first few pairs. “Twenty minutes of old maid it is then.”
Seto had just pulled the joker from Atem for the fourth time when he could feel the knot inside him slowly deflate. He dropped the cards. “Oh thank fuck.” It’s not that he disliked being close to him, but the feeling of being constantly filled with cum for such a long time was odd, to say the least. He manoeuvred himself out of Atem’s lap and off his dick. Atem stared at him. Specifically, the space between his legs. “What?”
“I expected it to. You know. Leak.”
“That’s not really how this works.”
“Oh.” Atem stared at his stomach instead. “Isn’t it uncomfortable?”
Seto dragged a hand over where Atem’s dick had been for the last twenty minutes. “It’s a bit weird.”
Atem stretched out his hand as if to touch it, then dropped it. “Won’t it hurt? If you were to spend your whole heat with someone and got knotted every time? Wouldn’t it swell?”
“I’m not sure what you’re imagining, but omegas’ bodies actually have a capacity for that.”
Atem’s face went red. “A storage room for cum…” He muttered and Seto was sure he imagined something ridiculous. He gripped Atem’s wrist and pulled his hand so it would touch the space between his abs and his dick.
“Feel that? There’s a pouch, because the body needs space for the ovaries and everything that comes with it. That includes cum.” He watched Atem feel around the space as if touching a foreign object. “Didn’t Yugi have this too?”
“I never really paid attention to that. I guess there could have been something like that.”
Seto shrugged. “I suppose it’s not an area one generally looks at.” He slowly got to his knees, reaching for his discarded clothes. He would have liked to stay longer, he wouldn’t have minded spending his whole heat with Atem, but he could feel the strain on his body. Who knew what kind of effects staying too long would have. “I have to go.”
“Yes.” Atem had noticed too. “You’re starting to disintegrate.” Seto dressed the bare minimum, bundling the rest of his clothes up. He was already starting to feel hot again and it wouldn’t take long for him to want to rip every single piece of clothing off of himself again. He stood, a bit unsteady at first, and looked at Atem, who hurried to put on his tunic to at least look presentable.
“You still owe me a duel. I will return for it, no matter what.”
“Of course you will.” Atem’s smile was soft. “Until then.”
“Until then.” Seto confirmed, and with that, he left.
“Nii-sama.” Mokuba received him with a worried look. “Is your body okay? Do we need to make adjustments to the cannon?”
“Yes, we have to.” Seto slipped into his coat. “I’ll be taking the calculations and analytics with me. My body didn’t last very long in Aaru. There’s got to be a way for it to be more stable.”
“Yes.” Mokuba sniffed. “You should stay home. Your heat will start soon.”
Seto figured his scent must have been more subdued now. Mokuba didn’t know of the mark, so of course he must assume that his heat hadn’t started yet. “I’ll take the necessary precautions. Don’t count on me being around for the next couple of days.”
“I’ll stock up on water.” Mokuba began tapping on his tablet. “Shall I add detergent as well?”
“Yes.” There was no way he’d be fine with his usual procedure of dealing with his heat after having had sex with Atem. He would probably need more extra sheets than usual.
“Got it.” Mokuba mailed the staff the notification. “Let’s go home then.”
Seto spent the rest of his heat cooped up in his room, thrusting his fingers inside of himself and rutting against pillows until he was too spent to move. Then he’d sleep, eat the meal in front of his door and start all over. It was nothing new, but he found himself pressing on his mark more often than not, whimpering Atem’s name into his pillows and feeling so, so empty. He wished he would have at least taken something with Atem’s scent on it home. By the third day, he could feel it starting to subdue again. It was shorter than his previous heats when he was off suppressants, but Seto chalked up the change to the fact that he was mated now. Who knew, maybe his next heats would be more bearable. Seto welcomed the thought of that. By the fourth day, he could already meet Mokuba in the kitchen again.
“Good morning.” He took the pot of hot chocolate Mokuba had made and poured himself a cup. Mokuba raised an eyebrow, but didn’t comment on it. It wasn’t unusual for Seto to crave sweet things after his heat.
“Good morning nii-sama.” Mokuba took out a second bowl and filled it with rice. “You’re back early.”
“I was surprised myself.” Seto considered the thought of telling Mokuba about mating with Atem. It wasn’t like he intended of keeping it a secret, but doing so would be indirectly admitting that they had sex, which was not a talk he wanted to have, especially with Mokuba. He supposed he would tell him if it came up.
‘“Are you gonna go back to work today?”
“I think I will. My pheromones should be weak enough not to distract the other scientists. Though I will still work mostly in my office.” After spending the rest of his heat craving Atem, there was no way he wouldn’t immediately go back on improving the dimensional cannon. Mokuba likely guessed his thought process, so he just sighed.
“Please just come back before dinner. Your body still needs to catch up.”
“I’ll see what I can do.”
Mokuba groaned and pinched the bridge of his nose. “Fine.”
Research wasn’t progressing. Or at least it felt like that to Seto. There was progress, sure, but it wasn’t fast enough to his liking. If only there was another way to test how well his new calculations would implement without going himself. In movies, they usually used apples to test teleportation. Seto wished he could use an apple. But someone would have to observe said apple and note down any observations on it, up until the point of it disintegrating. And he didn’t have anyone for that. Simultaneously, he worked on his calculations on how to bring someone from Aaru over. Permanently. As he didn’t have any plans on staying in Aaru himself and wasn’t one for casual dimension hopping either, Atem would have to stay with him. Since they were mates. Or so he told himself. Really, it was just an excuse to keep Atem around. Other days, he found himself pausing mid calculation, resting his hand on his neck, fingers feeling for the mark under the fabric. Mate. Atem was his mate. He was Atem’s mate. A deep inhale. A silent fuck yeah. Back to work.
Mokuba visited him occasionally, if only to check up that he wasn’t working himself to death. Sometimes he brought food, or coffee. More often than not, Seto found himself nauseating at the smell of the coffee, claiming it to be too strong and Mokuba would have to drink it himself. Mokuba would use these opportunities to give him lectures on how he wasn’t taking care of his body as properly as he should, considering how his body started to reject the very fluid Seto had built his work schedule on. He came around more often, bringing water bottles instead until Seto told him to stop because he was running to the toilet every 30 minutes. By the time Seto started throwing up, Mokuba told him it was high time for his body to protest working 18 hours a day and dragged him home after Seto had spent an hour on the toilet, switching between vomiting and drinking water and vomiting again. Seto had let himself be dragged out of the lab, but not without grabbing his hard drive first. Mokuba had confiscated it immediately.
“Say. You didn’t sneak any other research materials home, did you?” It was his sixth day of being grounded via little brother when Mokuba discovered him throwing up yet again.
“No.” Seto lied. He may or may not have synced his work PC with his home PC.
Mokuba sighed. “It’s just… you haven’t been getting better. I thought you worked too much, but maybe I should have taken you to a doctor instead. It could be something nasty.”
“I’m fine.” Seto wiped his mouth with some toilet paper. “As you said, my body just doesn’t like me working and I need a break to recover.”
“Right.” Mokuba sounded unsure. “If it doesn’t get any better next week, I’m calling a doctor.”
“Fine.” Seto flushed his vomit down the drain and got up. “If it makes you happy.”
“It makes me happy, yes.” Mokuba handed him a cup to flush his mouth with. “God, it’s almost like you’re pregnant, with the constant throwing up. I should have you take a test.”
Seto didn’t reply.
“I mean, I won’t, I was there for your last heat. There wasn’t anyone else.” A beat of silence passed. “Sorry, that was in bad taste. I shouldn’t have made a joke like that.”
Seto put down the cup a tad too forcefully.
“Nii-sama? Look, I really am sorry.”
“Fuck.”
“What?”
“I said fuck.”
“Uhm. What.” Seto could see the confusion in Mokuba’s face. “I really didn’t mean to-”
“It’s fine.” Fuck fuck fuck. “That wasn’t directed at you.” He was such an idiot. “I’ll go to my room.” Of course. They didn’t use any contraception. He had been in heat. Atem knotted him. The chance was so much higher than just a random one night stand. Seto groaned and dragged his hands over his face. “You know what? Buy that test.”
Mokuba had gone still. "Nii-sama…. did you-"
"Yes." Seto didn't want to hear the full question out of Mokuba's mouth. He pulled down his turtleneck to reveal the mark. "We even went a step further."
He could hear Mokuba suck in a harsh breath of air. ".... okay. Yeah. That makes a lot more sense now. The shortened heat, the coffee nausea, the vomiting…. I'm guessing it's morning sickness?"
"Might just be."
Mokuba mimicked Seto, dragging his hands over his face. "Fine. I'm buying that test. If it's positive, I have a dead pharaoh to strangle."
Of course Mokuba wouldn’t actually strangle Atem. He knew his brother well enough to guess that he was probably the one who had initiated it. Though that didn’t change their current situation. Mokuba grabbed the pregnancy test that promised the earliest results and one from another brand, just so they could make sure the result wouldn’t be a false positive. And another. He needed to make absolutely sure. This was his brother. Seto Kaiba. He wouldn’t tolerate skewed results. Mokuba decided to just take one of every kind. Making his brother pee on some little plastic thing ten times for worrying him like that was petty revenge, but he was feeling petty. Great. Now all he needed was a heap load of chocolate to treat himself because Seto fucking Kaiba had decided to get himself knocked up and Mokuba could already feel the frustration coming because that meant his brother would not stop working on the dimensional cannon until it was safe to bring the father here and it would be up to Mokuba to make sure that he took care of himself and the fucking baby inside his fucking stomach. Mokuba wanted to slam his head against a wall. Yeah, he deserved some chocolate. A shit ton of chocolate. And then he’d call Sera and rant to her. Yeah, that sounded like a plan. He entered the aisle with assorted sweets.
“Oh, hi Mokuba.”
Big mistake. Yugi and Jounouchi. Mokuba would just ignore them on any other day but right now he had a basket full of god knew how many pregnancy tests.
“Oh, it’s Kaiba’s little brat.”
Not anymore, no. Mokuba wanted to laugh. He wouldn’t be the youngest in the Kaiba household anymore. ‘Kaiba’s little brat’ would be an entirely new title for his brother’s kid and- oh god he was going to be an uncle. Mokuba groaned. He was too young to be an uncle. Couldn’t his brother have waited a few more years? Who had a child at eighteen nowadays? Mokuba grabbed the nearest bar of chocolate and began moving down the aisle, just shovelling whatever he liked in the basket.
“Having a party?” Yugi popped up beside him.
“Something like that, yes.” Mokuba skipped past a dark chocolate treat. Nothing bitter, thank you very much.
“Sounds fun. Gotta love a party with chocolate, more chocolate and-” Jounouchi threw a glance in Mokuba’s basket. “-pregnancy tests?”
“Yes, it will be very fun. Pee everywhere. The funnest party ever.” Mokuba’s voice dripped with sarcasm as he selected the next chocolate treat. “Gotta love pregnancy tests. They’re so fun, especially when they come out positive.”
“Mokuba.” Yugi paled. “You didn’t-”
“Oh, they’re not for me.” Mokuba debated if he should get some cookies as well. “I just happen to know a very irresponsible person.”
“Ah.” Good, it seemed like Yugi wouldn’t pester him anymore. He actually liked Yugi but he was in no mood to answer questions.
“Don’t tell me Kaiba actually managed to fuck with someone.” Of course Jounouchi would be the last boss. “Kaiba? Mister I’m so uptight I wouldn’t even touch my own dick?” Well that was just blatant defamation. Sadly Mokuba knew all too well that his brother masturbated. At least during his heats, he had to. Outside of heats, he didn’t know. He didn’t want to know either.
“I’m not talking to you about my brother’s sex life.” Mokuba decided yes to the cookies. Maybe he should get ice cream too. “If you’re so curious, ask him yourself.”
“Wait, Mokuba.” Yugi again. Mokuba wished Anzu was here. At least she kept them in check. “Kaiba is back from Aaru, right? Does that mean-”
“Oh my god Kaiba fucked the pharaoh.” Yep, he couldn’t have put it better himself.
“Jounouchi!” Yugi hissed. “We don’t even know if- if it’s really Kaiba these are for.”
“What? Dude reeks of omega. If there’s someone Mokuba would buy these for, it’s him.”
“That’s-” Yugi bit his lip. “Mokuba, are they really for Kaiba?”
“I’m not saying anything until I got the results of every single test.” Mokuba decided he had enough cookies. Next was ice cream. “Not who it is, who it was with and I don’t care if you’re concerned because it might concern a guy whose spirit you housed for some time. Now if you’ll excuse me, I’m going to use my brother’s money to give myself cavities.” He pushed past the two and when they weren’t following him, breathed a sigh of relief. This was a family matter. If they wanted to intervene, they’d have to try harder. For now, he was going to buy so much ice cream until his headache was from the cold instead.
“There.” Mokuba dumped a shit ton of pregnancy tests on Seto’s bed. “We’ll talk again when you’ve taken all of them. I’m going to watch TV and eat unhealthy food.” He left the room and Seto was left with what looked like maybe ten, twenty tests just sitting there. Better get this done sooner rather than later.
Peeing on a plastic stick was not Seto’s preferred method of doing things, but he had done it sixteen times by now and was currently doing it for the seventeenth time. It was amazing how many different brands and types of tests there were. All the other ones were sitting on the edge of the bathtub, developing their results. Seto hadn’t looked at them yet. He wasn’t sure if it was nervosity or certainty about their results. He set the last one aside and washed his hands. Wait. Don’t look. Check watch. Wait some more. Leave the bathroom. Get something to drink. Fidget for twenty minutes. Return to the bathroom. Check the first test. The second test. The third, the fourth, the- the seventeenth. Seto took a deep breath. Let it out. He collected the tests and threw them away. Messaged Mokuba. Sat down.
Positive.
He’d have to tell Atem.