I'm glad you like it! I wanted something big and dramatic lol. Alright: I think her blood status wouldn't be a secret, but it isn't something she would advertise. I was going to ask about their relationship too! I almost added something with her looking for him at the end of the post, but refrained because I wasn't sure. I'm thinking They might not be very close right now, perhaps they were friends when they were younger, but friends and social circles have taken them away from one another. Divination is her best subject, I'm thinking maybe something with a tutoring situation on how to bring them together and force them to spend time. Also, I'm thinking maybe the performance might be the first time he's seen her in sometime and she would be beautiful, so it might make an impression hehe. 
I really like your character too! I think you really captured the elitist side of the pure blood culture. I hope you don't think my character has sunshine shooting out her butt, but I wanted to make her a very stark contrast to what I assumed would be qualities you would use in a new you-know-who. :-) I promise she won't be perfect heh. 
Can't wait for your post!