give it away.

Oughgg having the realization that almost every single "creepy" thing Nikki/"Nikki" does are also things that a lot of rape victims do, specifically ones that a lot of non victims find unpalatable. Acting out, fawning over her abuser, self harm, wetting herself, getting into/writing about dark and taboo topics, et cetera et cetera.

Re: your tags - I would argue that Sarah deliberately misreads the situation to benefit herself and that she is one of the people who takes advantage of Nikki. Even before the car conversation. Sarah knows that Ian wants Bear at the party alone. And she purposefully tells Nikki that she should come. She knows exactly how weird Nikki has been. She invited Nikki specifically to put her 'weird' behavior on display. It's emphasized for a reason that she and Ian have been talking about it. Ian correctly reads the situation (and does nothing), and Sarah, now armed with a public display, takes those words and uses them against Nikki instead.