Happy to hear that I've inspired you to get started on writing a series of your own ^^ I'm not familiar with FGO myself, only watched the UBW anime as a reference for some comms earlier this year, but I'll make sure to give it a read ^^

That said, there already exists a pretty good FGO-oriented story by Deathstalker, here: http://depravityrepository.org/forums/showthread.php?tid=1180 Not saying this to discourage you, just pointing out some scenarios from that verse that were already done by another author that you might want to avoid ^^