Hi, Andrea! I'm Ally! Welcome to the game! I play many a character.
Oliver Wood: He plays Keep for Puddlemere and obviously would know who Sean is because Quidditch. Oliver's pretty easy going and is friendly to most people (be warned, though, he's a pretty shit friend), so I think he'd definitely get on with Sean if Sean wanted to get on with Oliver?
Terence Higgs: Recently became a Hitwizard after 10 years in the Muggle military. He would have been a year below Sean in Hogwarts and played Quidditch for majority of his time at school, so they'd at least be aware of each other's existence? Higgs is the nicest Slytherin in the world, so he'd be friendly to Sean?
Aisling Astor: Plays the violin for Quake the band. She was Sean's year in Hogwarts but in Ravenclaw, so they would definitely know each other? Aisling's a bit... posh, so she can come across as rather cold but she's quite nice, really ;)
Zacharias Smith: Is an asshole. He's an investment banker and has a personality of one. He wouldn't know Sean, I don't think, and he doesn't really care to? Sorry.
Evan Potter: The youngest of the Potter children! He's at uni, studying magical architecture. I don't think he'd know Sean either since he doesn't really like Quidditch and is too young to know Sean from school?