My edgy fanfiction idea:
Truck-sama helps Kiritsugu portal in to murder Lect and Pals, he joins the military of the country that blonde homunculus princess belongs to and moves up the ranks, he marries the princess and begins planning a coup with her, the coup succeeds, blonde princess person dies in her sleep from "natural causes", Kiritsugu consolidates his power and has the empire develop superior magical weaponry, he pulls a Zero Requiem, it succeeds, the world is semi-peaceful for a time.
Epilogue: Lect and Meria make each other miserable in heaven(?), Meria eventually ditches Lect realizing she can do better, she meets a bunch of bishie angels who all love and cherish her, Lect becomes Lect the Tomato via a sadness-induced lobotomy, the rest of Lect's harem went straight to hell(?) and became members of Lucifers endless harem of awesome, they couldn't be happier.
The End.
Edit: I touched up the grammar a bit.