And if Shirou was not the only children found by Kiritsugu in the flames of Fuyuki ?

This is going to be a crossover between F/Z and Akame Ga Kill. It's set 2 years after F/Z. The alternations are Saber got doused in the Grail liquid, giving her a physical body, Angra Mainyu never cursed Kiritsugu. Kiritsugu retrieves Avalon back from Shirou, Saber understands why he did what he did, that was destroy the grail.

Within a nation filled to the brim with corrupt nobles and suffering peasants, how will an honor bound knight, an apprentice of the Kaleidoscope and the one who seeks to save everyone fair within it? One things for sure, with their swords and magic, a revolution is about to occur.