I have no problem with Nessa meeting her. Nessa is highly... abrasive sometimes, but she has also become something of a dreadful flirt, but that's all an act because she wants to keep the fact that she is a werewolf a secret. So Mia probably wouldn't know about that. However, until we have a separate plot for them, maybe we can start with their time in classes? All students are in one thread for each class, so Nessa and Mia would be in class together all the time, which is convenient for testing them out.
Maybe we can start with Mia in Apollo's class, and see how he reacts to her. I don't expect him to assume students are messing with him because they think he's good looking or whatever - he sort of knows that he is, but doesn't react to it as others might, if that makes sense. So he would probably ask to speak with her after a while, so we could have the class thread but then, once I get caught up on that thread I could start one and set it a couple weeks after classes start, where he's asked to talk to her after class?