idk if you’ve gotten ur answer but I suspect Ferid has memories of his previous lifetimes and is sick of being reincarnated. It why he’s so hell bent on the topic and just wants it all to end ever since he was a kid.
They hint at this with his backstory and also in his convo with Crowley. Crowley was confused but Ferid was saying things like “I’m the type that can never forget things” “I get the feeling we’ve gone through a lot” “how many years has it been since we met again…it’s been a while, a really long while” Crowley is confused the entire convo since he has no recollection of his 439 other lives.
This is all speculation though, we know he needs to get stronger for his goal. His exact plans are still a mystery
I understood everything until this update. Like??? Why is he killing everyone?