I love the trope of Someone (at least seemingly) Nice Gets Horribly Corrupted Into A Monster and Joyfully Embraces It

and then they spread it around

Of course there's also the companion trope, "Villain absolutely physically corrupted and destroyed beyond recognition by their lust for power or their own hubris", aka the Resident Evil classic

No remorse, perhaps a bit of sympathy for their younger more innocent self, but I love a Sadism Unlocked and Loving It villain, not even "was evil the whole time" thing

Hey I have a story kinda like that first bit, but the dude’s completely unaware that he’s changing

oooh yes? I'd love to hear about it

The guy is an AU version of my main character, Tapeworm, who’s a monster anyway, and this version of him went by Dr. Wormwood, until he forgot it
He was highly regarded before he started changing, and would mess around with gods and other entities to both help people and get what he wanted, but kept that as secret as he could

and the things he’d offer in exchange would vary, a lot of times is was a sacrifice of course, and at some point, he wanted to be able to better study werewolves, and asked a god of flesh to be able to make them shift by touching them, even just parts of them. But, in turn for doing that, he would also turn into a monster, but very gradually

and he would notice smaller things with it, like his eyes looking weird, but wasn’t fully aware that he was changing completely, and the process probably takes YEARS and with how much his body has to change, he’s in a lot of pain and loses himself mentally, forgets everything about his life as the mind of the beast takes over

And he of course terrorizes the town he lives by and empties it out because of his perpetual hunger

ooooh

yes that's excellent

Thanks, it’s also mostly based off of dreams I’ve had

hey, dreams spit some pretty great ideas

Yeah, I take a lot of inspiration from them

same