All imma say is my boy Flynn better be ok and or with Chase. I've started one of the Leo routes and I can even tell that he cares about Chase more than the others. I find that Chase probably reminds him of Sydney. Also I feel so bad for Flynn because while Leo and Chase had each other, Flynn was gay and alone, had to lose his best friend, and cover up a murder. He is in so much conflict that I hope he gets some resolution to.
Even though i agree that Flynn is probably one of the guys who care for Chase the most (i would even go as far as to say he probably loved Chase) i don't see a future with him ok. He turned into the Monster of Echo becoming a timeless being. The most i can imagine is Chase and his monster form facing eachother in the sequel and Chase like sacraficing himself to safe the two new main protagonists from his old friend. Also Flynn liked Chase way before Chase was possessed. Flynn did imply he liked Chase alot more when Chase was snarky and had a sharp tongue as a kid. Leo only really started liking Chase after he was possessed so Flynns love is more true to the real Chase.
https://archiveofourown.org/works/28432443
There it is, I may have gotten carried away with it though and I'm still working on the next parts.