I think I've mentioned her on this meme in the past but I feel like out of all the Evil Residents the one that'd suit you best is Mother Miranda, the big bad of RE8 who turned herself into an immortal fungus angel in her quest to resurrect her dead daughter using a mycelium hive mind. She like sucks a lot more morally than your usual type BUT

She does suck in a way that's fascinating and I think you could have fun digging into that

Like for one thing she was a female biologist in the early 1900s before the whole mushroom angel thing which is neat enough unto itself but also you specifically do a really fun job of breaking down characters who spend most of canon presenting themselves in a very specific way and disassembling their carefully curated image to get at what's underneath

what's underneath seems to be a lot of fungus

which is cool!

It's a lot of fungus and fucked up obsession quest bullshit mostly. Admittedly she's not the deepest character as she exists in canon but you could do things with the scaffolding provided

and I do love to do that!