It's Margaret with a third so I'll make this brief since my time in post out-of-character has been adding up.
This is Echo Rutherford (in previous games maybe Echo Driscoll or Berlin). She is one of those spitfire girls with a mouth that works faster than her mind, words tend to come tumbling out at a mile a minute. You can count on some strange references, a lot of popular culture, and sarcasm. She is friendly to everyone, and sometimes it even comes out sincere. Just teasing ;) She can be quite the sweetheart, but she will also do her share of eye rolling and condescending comments.
So... friends, enemies, et cetera. She has a man, but that's a secret - shhh. Other information that you may find useful is that she is a sixth year Ravenclaw and a Muggleborn.