Maybe we could have a half demon/ half human student who's trying to be good but gets hunted by his/her demon family, thus exposing themselves to Mirela? 

Maybe a witch can come later? Hmm, in the Netherlands the first week of college and university is introduction week where the different student groups introduce new students to the student life and the city. There's games, partying, drinking and having fun. Perhaps this witch could come in after introduction week, when classes actually start. We'll have a better story setting develloped then so we can work out what she wants then. Or would you rather have the tension from the start?

I think it would be most fun if the person living on the top floor with Mirela (I think it's a girl) would be non-magical.. Maybe she can knock on the door at the least appropriate times, or she forgets the shut door polcy and just walks in.kind of a comic relief character to keep Mirela on her toes.

Rachel is quite short and has long brown hair and an average face that just blends in. She has soft features, barely wears make-up. She is the lead actress in the theatre she showed the playbill from. She is a nice person, always willing to help people, always wanting to see the best in people but that can make her a little naïve as well. I'll add more description as you meet the people.

Another plot idea: Perhaps something has gone wrong and Mirela's student pass isn't working. They send het to the IT department, (of course it's later in the evening) where she meets my non-magical IT character being hunted by a demon?