In Season 15 of Supernatural and Season 5 of The Boys - Chuck is left with only two more worlds, and decides to have some fun. One world is Y/n, Sam, Dean and Cas’ world, the original world. The other is ‘The Boys’ world, with Soldier Boy, Mister Marathon and Malchemical. To get the Winchesters off his back for a bit, Chuck transports Y/n, Sam, Dean and Cas (along with previous cooperatives Jack Kline, Lucifer, Gabriel, and Crowley) into ‘The Boys’ world to help Butcher and his team in the fight against Homelander. In other words, the crossover where Chuck finally starts moving his toys between his different play sets.
In which Y/n was a victim of the fire Bobby started in Minnesota, and lost her family at the age of six. Sixteen years later, she joins the 118 but little does she know her new Captain just so happens to be the man responsible for the death of her family… and his own. As Bobby takes Y/n under his wing to make his past mistakes right, cue betrayal, drama, tension, action, family bonding, forgiveness and an unlikely enemies-to-lovers romance between Y/n and Buck, the overprotective golden retriever of the 118 (who just so happens to see Bobby as a father figure)
After Dean dies on a hunt way before he was supposed to, a reaper accidentally binds his soul to a stranger’s soul who died at the exact same time. This meant that any injuries or feelings - physical and emotional - that Y/n or Dean felt would be mirrored in the other person. After both of their souls are returned to their bodies, Sam and Dean track down Y/n and are left stuck together in the bunker whilst they figure out a solution. What starts off as anger and frustration in the beginning every time either gets both of them hurt gradually changes into tiny twinges of guilt over time, and it becomes impossible for them to hide their growing feelings for each other. As Sam gets closer to figuring out how to un-bind their souls, Y/n and Dean become suddenly aware of something: they no longer want to sever their connection to each other.
After being kidnapped and tortured by Hydra on a mission, Y/n is reminded of repressed childhood trauma and suffers from PTSD and panic attacks. Bucky Barnes is reminded of his own trauma and decides to help Y/n cope, but finds himself falling for her in the process. Y/n is 22 years old, and has the ability to manipulate how light, sound and forces interact with the cells in her body (basically she can turn invisible and packs a hard punch)
Buck has been keeping a secret from the entire 118 since the moment he first joined - he has an adopted daughter. Oh, and him and Eddie have been dating for 7 years. Buck adopted Y/n when she was ten years old, after he moved to LA for a new start. Buck and Eddie have been secretly dating and co-parenting Y/n and Christopher, but now Y/n isn’t a kid anymore and she wants to be a firefighter. Overprotective Buck and Eddie eventually agree to let Y/n start training, on one condition - that they can secretly get Bobby to accept her into the 118 where they can keep their eyes on her. Y/n is 19.