Hi Sammy! I'm Heather and I have five kiddos here, three of whom will be particularly relevant to Roger.
~ravenclawlari is Larissa Samuels, also of R6, and Hamish's BFF, so they'll definitely know each other. She wants to go into Quidditch healing and is mad on Muggle sports. Roger would probably know some of her personal history, such as losing her father during second year and the fact she speaks with a South African accent through her Afrikaner mother.
~victoriaregina is Vicky Frobisher of G6. Probably in a few classes together, and as a Muggleborn, Roger may have seen Vicky's dad on TV or heard of him (he presents news programmes but is a wizard, planted to avoid suspicious news leaking).
This guy is Leon Beery, previously Ravenclaw prefect and now Head Boy. Fairly lax, apart from when people REALLY cross the line. Wants to be an actor after Hogwarts.
I also have one each from the foreign schools - ~_dumspirospero_ is Anais Bolduc, 6'0 Quebecoise glamazon and captain of the reigning Quidditch champions at her school. She's a Chaser and wants to go pro.
Finally I have Anzelm Szczepanski of Durmstrang - a Polish 7th year and Viktor Krum's best friend. He's a Beater but wants to become an Auror. Pureblood, but blood traitor through and through, he said. Very straight talking and an activist of sorts.