Another AU that my friend and I often rotate in our minds that I wanted to share, because why not?
After Senku was shot by Stanley, he survived but was a bit worse. The fear of the enemy's power was more intense; maybe Stanley even shot a few more warning shots. Whatever the reason, Ryusui took the heavy decision of a retreat. Get the scout team back to the boat and leave. A lot of protest. What about Gen? They just have to believe in their mentalist that he will be able to keep himself safe until they return more prepared. The Perseus leaves, Max and Carlos jump quickly aboard.
Xeno announces that the children have run away with their tails between their legs after Dr. Senku was successfully taken out by Stanley. Gen feels dread, panic, and heartbreak. But he doesn't resent them leaving him behind. He is relieved he didn't lose anyone else, because losing Senku just destroyed him.
When Senku recovers enough, realizing they are on the ocean and they have left Gen behind, he is beyond angry and resentful. And Ryusui takes all the blame on himself. They need to retreat, prepare better, and return to save Gen.
Gen grieves Senku for weeks, quietly and when nobody is looking. But once he is done, he wants to keep Senku's legacy going. To do what he wanted so much to do: Revive humanity and stop Why-Man. For that, he needs a scientist, and he only knows one scientist here...
Getting into Xeno's head is a very slow process. He does what he needs to do to get in his good graces, and also Stanley's. He pokes and probes Xeno's brain. There's no fixing him, but he can use enough therapy knowledge to get the man off the dictator track a little bit. And when he finds a sliver of guilt about ordering Senku's assassination, he stabs into it and twists the metaphorical knife hard.
That's when Gen shares what Senku's dream was. Speaking so fondly of him. It reminds Xeno and Stanley of each other. Then he drops the Why-Man bomb and says they need to stop it. That immediately put them on alert, and Gen shares what Senku's plan was to revive a lot of people and build a rocket to stop them before they rain down petrification on them again. They agree to it, and it's a deal. Gen shares what he knows of the revival fluid, enough for Xeno to figure it out. Then they get to work.
When the KoS returns to the shores of America, it has been months, maybe even years. They have prepared more, created more technologies, and have more tricks up their sleeves. Senku has barely rested, having Gen on his mind constantly, hoping his mentalist is still safe and alive. That he doesn't hate them for leaving him behind.
When they are discovered, they are not welcomed by gunfire, but Stanley and a few of his soldiers announcing that things are different now. They can thank their little rat for that. Stanley is surprised that Senku lived, but inside, he is a little happy for Gen's sake. The kid has a way to worm himself into others' hearts. The American colony is thriving. With more people, it has grown a lot. And a large construction site where they mention that's where the rocket will be built. Senku and the KoS are gobsmacked. They weren't prepared for THAT.
Stanley brings Senku and a few of his friends into the castle, and before they can enter, they spot him. Gen, their mentalist. He's talking with people, seemingly doing some management work. And when Gen spots them, he drops all the papers he was holding, eyes locked on Senku. His whole body sways with emotions, and Senku runs to him to grab his arms and keep him up, but that only makes it more real for Gen to be touched by him. He cries out his name and hugs him tightly, sinking to his knees and taking Senku with him. He keeps saying how he can't believe it's really him. Senku hugs him back and apologizes over and over for leaving him behind. They're finally reunited, and they both feel alive again.
I. AM. CRYING!!! ππ
I've thought about something similar, but yours is so much more emotional! ππ
Especially if they are gone for years and Gen the whole time is thinking Senku is dead. (Worse is if they weren't together and Gen never got the chance to tell Senku how he felt)
And I agree with Stanley, Gen does have a way of worming his way into people's hearts.