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Whenever Lily Potter thought about that awful day, she would drown in her grief. Her precious boy and loving husband were gone in a blink of an eye because of one madman. She would never forgive herself for going to the store that night. There was an emptiness in her chest that could not be filled, no matter what she tried.
The war continued over the next few years. Throwing herself into the research of obscure spells and then using them on the death eaters, was the only way Lily was able to tread water. She was the final one left in her friend group by the time the war officially ended with the death of both Voldemort and Dumbledore. Their world was in shambles and the only way for everyone else to get through it was to rebuild.
Lily on the other hand decided that her best course of action was to go work in the Department of Mysteries. The only time she felt at peace was when she was finding forgotten magic. Her spellcrafting in the war made her a great candidate to research the intricate magic of the universes. And wasn’t that a surprise when she found out that the plural use of universe was not an accident. There were multiple universes with an abundance of variables and outcomes, according to their calculations.
One day, the department was trying to narrow down parameters for what kind of world they would possibly want to visit once they figured out the right spells for travel. It dawned on Lily that she could use her own parameters to try and find a universe where she could be reconnected with the family she lost. She started brainstorming day and night for what kind of place she would want to end up in.
She never wanted to insert herself in a world that had a different Lily living happily with her son and husband. So, she immediately took out that requirement in the calculations. She also decided that at least her son needed to still be alive in the universe and that she wanted him to be younger than her since she thought it would be even more awkward if she joined a world in which her son was way past her own current age. Or maybe a world that had a similar timeline as her current one.
She was able to live many years knowing James and wanted those years with her son as well. Her calculations, unfortunately, were not going well for worlds that had both James and Harry in them, along with worlds where James did not already remarry or was in a serious relationship. While it stung for a moment to realize that James could move on, she also realized that she would want him to be happy, no matter the time or place.
When her parameters became too specific, her calculations started to fail. So she turned her research to figuring out how to actually travel to another universe. She tore through the Potter and Black family libraries reading any tome that could possibly help. She finally read an old piece of rolled up parchment that mentioned Rowena’s library at Hogwarts. Minerva graciously let her use the main library in the school to try and find Rowena’s library, as long as she shared the location if she found it. It took her less time than she thought to find the beautiful little library with stained glass windows just off the charms corridor. The ancient texts revealed magic and histories long forgotten. Minerva was ecstatic when she showed it all to her and allowed Lily to take the information she needed as long as she returned it at a later date.
Reading through those texts revealed that the veil in the death chamber was thought to have been the way to the Otherworld and worlds beyond them. Day after day Lily found the puzzle pieces she needed to make the journey happen. A mixture of runes carved onto the arch of the veil and spells casted right before she walked through were needed.
She finally went back to the parameters she was setting for the world she wanted to go to and realized that the main criteria she wanted was a world where her son needed her help. She added back a few other ones from her earlier calculations, like worlds that already had a Lily. When she was finally done with all of her calculations and the simulations she ran worked perfectly, she started to prepare what she would bring on this journey.
She packed away all of her research and a majority of the books she used, except the books she sent back to Minerva along with a note thanking her. Since she did not know the exact circumstances of the world she was heading into, she also took out all of the money in the Potter vaults and some of the artifacts that would be helpful, such as the invisibility cloak. The last thing she did to prepare was pack enough food for a few months just in case.
When everyone was already gone from the department that evening, Lily shrunk down the bags of everything she was bringing into her pockets and headed toward the death chamber. Once she was there, she carved the runes and cast the spells. The veil lit up and called to her. Lily looked around the dark room one last time and took a deep breath as she walked into the veil.
She saw a familiar dark head of hair falling towards her as she stepped through.
“It’s not your time to go, Sirius.” Lily pushed her old friend to the side so he would miss colliding with the veil.
Taking in her surroundings, she had to duck to miss a curse heading her way. It fizzled out in the veil behind her.
Sirius sat up gaping at her. “Lily?”
“I’ll explain later, I need to help you lot end this.”
She spun her wand in an intricate pattern and everyone froze.
Green eyes met green.
“Hello, my darling boy.”