A very unique idea, I know, but one I really want to see. "Corrupt the Cutie" is a trope where the villains get their hands on a (relatively) innocent/sweet character and corrupt them, leading them down the path to "the dark side". This takes many forms. Sometimes they're tempted somehow, or pressured; often they're abused psychologically, physically etc. It's very common in the hentai area, with a very specific manner of abuse that somehow manages to simultaneously overwhelm them with a thirst for even more. What I'm looking for is stories in which a (main or secondary) heroine is somehow "corrupted", taken away from the hero and turned so that she either becomes one of the villains herself or happily embraces whatever sort of life they came up with for her; then, even though she's completely turned against him, the hero doesn't give up on her, and ultimately manages to take her back. Not necessarily a full return to the person she was before, but still a return to his side. I honestly don't care about the medium or the rating, whether it's manga, anime or LN, or whether it's something you'd be OK showing a grade schooler or something you'd find in the 18+ section (truth is I started wanting this because I inadvertently recalled seeing an 18+ story that did this and wished for something different). If it's 18+ (I don't know if that's forbidden in this section) feel free to PM me, but again anything is fine.

Got example?

Rokkon Shojo
TeppenMezashiteTondeAruYo
Let justice be done, though the heavens fall