Hiya, welcome to the game :-) I'm Kaylie, friendly neighbourhood mod and I have four characters already somehow:
Seamus Finnigan (openbottle), pub landlord. May not really remember Richard from school but will probably recognise him from around the pub. Depending on how Richard's PTSD manifests, Seamus may recognise it as his best friend (Dean Thomas) also suffers it. Has probably invited Richard to Battlescars but won't pressure him to come.
Dominic Chambers (knowhow) was a Ravenclaw, a year younger than the trio so... three years younger than Richard. He also started playing Quidditch the year after the TriWizard tournament so they probably faced each other on the pitch, but I doubt Dominic would remember him much outside of that. However, he can know Richard from around the pub too since its him who sets the rooms up for the various activities. I think they might get on? Dominic's got a bit of an adrenaline thing as well (he likes fast cars and fast brooms).
Lucy Spinks ([Bad username: adding value] was a Hufflepuff, Harry's year, but she's been out of the magical world entirely since Dumbledore's death. She might vaguely remember Richard from school. If he remembers her at all it's probably as the tiny girl who wasn't very good at magic and spent all her time studying like a Ravenclaw.
Greg Goyle (this chap here!), my newest. Probably doesn't remember him much from school or particularly like him. Just because he only really likes the friends he already has.