Appeal to Erin's judgment

You choose a neutral course, appeal to Erin's better judgment: Erin cares a lot about the sorority, even if she can be a bitch to the girls. This girl was even up here in Erin's room, so it's possible this is also some kind of test Erin's set up. As the redhead blubbers and accuses you of lewd misconduct, you try to present things matter of factly.

"Erin, there's some truth to what she's saying," you start. "I startled her when I came in, and I thought she was... ...someone else... But I gave her space, I checked her out, yeah, but I never was direct or wrong. Then, she flew off the handle, even tried to kick me in the dick. She's probably a little too sensitive, is all."

"Oh Miss Erin~ he's LYING!" The redhead shrieks, holding onto Erin for dear life and really trying to sell you down the river. "We ought to call the police!" The redhead's Southern drawl and her pouty, brat act is really convincing.

But, Erin takes your side.

"Listen, Jess," Erin's calm voice has a soothing effect on the redhead freshman, Jess, it seems her name is. "I know this guy here pretty well, and I'm not buying that he was doing anything wrong to you... at least... nothing that you weren't secretly asking for..."

Erin has disentangled the distraught ginger, Jess, from her and now the redhead looks like she might crawl into a corner and die. "B- b- but, Miss Erin..." She manages a weak plea and falls to the floor at Erin's feet.

"I - I - I... I would never..." the redhead's freckles are wet with tears, but she's at a complete loss. With Erin taking her side, she's lost her most powerful potential ally.

"I don't believe you, Jess, you're a naughtier girl than you let on. You can't just slander accusations at people for no reason." Erin says icily before turning her attention to you. "And, now..."

Erin locks her door with a click that makes the redhead's face drain of color. "Now, how should Jess pay you back for her antics... what do you think? I don't know if an apology would be... appropriate enough..."