Mark would have been in his year in school! Mark's also super gay and would have put his face on Vic's face if Vic had been interested. Also would've known him as "Ben", so whether Vic calls him that or Mark is really up to Vic. Mark's at a place in his life where he welcomes the nostalgia. Mark also has an adorable dog.
Pella's a fellow teacher. He'd only have known her in the last year regardless.
Annabel is also on staff, and though she and Vic are the same age, she actually didn't attend the Academy. We do say that Billy and Teddy are good friends with Carol and Cap, though, since Marvel and Owen were besties/dating/etc. and were close even after their breakup, so he'd probably have known Annabel for the last few years as Owen's girlfriend.
Same logic goes for Jes as Owen and Sam's sister.
If Luka was normal, he'd have been in school with Vic, but he's not, so he was graduating from Harvard when Vic was graduating high school. He's pretty friendly, though, and a fellow Sentry.