"Stiles. Stiles look at me." Derek ducked down again to try and see his face. "It was not your fault. Even if you said yes or you agreed to it at any point you obviously did not want it, if this is how you're reacting. It was coerced out of you. That is not consent."
The fact that a woman did this... Derek considered himself a modern man and did not usually let gender roles control him but he would never have thought a woman capable of this, of reducing someone - especially Stiles - to a frightened mess at just the thought of her and what she'd done. "Please, can you give me a name, or if you don't know a description. If she's in the castle then she's a risk to others. I won't tell anyone that you told me, I'll go to the Headmaster and say that I heard her threatening a student in the halls or something."