Kenzie is friendly with everyone so she will be with Lucien, but I don't know how close they'd be since she's 2 years older? Trish should definitely be friendly and I don't see why there wouldn't be potential for friendship there.
Viv is in the same house, but depending on how he is with her she's not going to like that she feels some sort of pull to him when he's close and doesn't when there's some distance. She's very innocent on the relationship front so I definitely don't want any corruption there, and with Gawain also being in their house there might have been some warnings there...so I dunno.
Cat has Skye for now, and Trish too. I dunno about Viv yet.
Septimus and Viv should be friends. Because music. Also she'd really like how friendly he is, I think. And my other sixth years (who aren't dating him :P) should probably talk to him more too. Especially his freaking roommate... >.>