Hi Sammy! I'm Patricia and I'm the mod here, so if there's anything you need, don't hesitate to ask. :)
I have three boys here, all of whom Roger will know (or at least know of):
Firstly, there's Cormac McLaggen (myownfanclub), fifth year Gryffindor. He's loud, childish, immature, obsessed with girls, Quidditch and his own awesome self (well, awesome in his own eyes, that is), but underneath all his braggart ways he's just an old softie. He's trying to rebel from his purist family but is failing terribly at it so far. He and Roger could probably have ego feasts together, if not for he fact Cormac is friends with Amelia (well, she tolerates his presence); he'll be friendly towards Roger to annoy her, but I can't see them ever becoming BFFs.
Then there's Hamish Fraser (this journal), whom Roger will know very well, what with the two of them being dormmates and teammates. He's a thick-accented, kilt-wearing Scot who, in spite of appearances, is actually very sweet and girl-shy - in other words, where girls are concerned Hamish is the anti-Roger. They can bond over being unusual Ravenclaws, though, as Hamish is terrible at theoretical classes (he had a D in his History of Magic OWL!) and having muggle backgrounds. Also, he's the identical twin of Cassius Warrington from Slytherin (they were separated at birth by their purist grandparents and only met at Hogwarts) but it's not hard to tell them apart since they actually prefer to accentuate their differences.
And finally there's Samir Karim (littlepharaoh), sixth year Hufflepuff, whom Roger will know from classes. He's a muggle-born from the posh part of London, but he's not in the least stuck-up. He's now living with his friend Barney's family, as his parents kicked him out after he came out, but he's trying to fight any negative feelings about it by putting all his energy in all the artistically-inclined clubs and by mothering his friends and housemates. He's very loud and hyper and likes to write in CAPITAL LETTERS when he's excited, which some people find a little intimidating. Also, since Cedric is one of his best friends he'll be Team Diggory all the way, but he'll still be nice to the other champions and their supporters in his loud, inimitable way.