The perfect example is Jessica. How she develops depends entirely on how Lena behaves before she meets Jess. But Jess is such a side character in ORS that it was really a fun Easter Egg more than anything. It would have been nice to maybe have a Jack that mirrors Ian's behavior in a similar fashion to how Jess mirrors Lena's, but alas...I like the idea of variable backgrounds but it should only apply to the two main characters. I guess cameo characters, unless you're named Jack, need some variability as well.
I don't really mind Lena's backstory being "changed" all the way into chapter 12, as much as some others. If for 11 chapters the player has done nothing but choose the slutiest options available for Lena, it would honestly perhaps make sense that she has maybe possibly always been slutty. Just as much as if she's been faithful to Ian or Holly, or even the likes of Robert, Ivy, or Louise it would make sense that she has a history of being a more faithful lover seeking long term relationships.