Did you ignore the second sentence in my first paragraph? I never said that Holly was incorruptable, I said that if it is in fact a corruption mechanic, rather than Holly coming out of her shell, then we're still a couple of chapters away from that. Hell, in every scene with Holly except the gym and the club in chapter 10, Holly still is dressing in her normal attire. I wouldn't even call what she's wearing in either of those scenes "slutty" either, just cloths that reflect the confidence that is growing in herself and her body.
If Holly goes home with Mark, we're at maybe like step three, after 10 chapters, if you're comparing to GGGB. Eva and Ashley had hit not just sex, but drugs, piercings, and slutty cloths by what I would consider the second or third chapter. Again, ORS is much more of a slow burn on any sort of corruption mechanic.