Hiya, Trixie! If Phoenix knows Molly and Margo, it's almost guaranteed she would know the Zabini twins. Christian and Apollo are fifth years, Hufflepuff and Slytherin respectively.
Currently, Christian is sort of recovering from a Quidditch accident at the start of the school year, and Apollo's mind is playing tricks on him when the full moon comes around. Because he was scratched pretty deeply by a werewolf, he has this irrational fear that he'll act up at the same time they do. I don't think anyone knows that he's paranoid about it, though, because he typically just acts like even more of a jerk than usual. On the whole, Christian is more friendly, Apollo is more of a flirt, but both boys can get into their moods.
I also have Katherine (Kit) Avery, who has an illness that keeps flaring up. Essentially, she doesn't know what's wrong because it hasn't really been figured out yet, but because she's pureblooded, her genes are all wonky and her body is trying to reject her magic. So she has bad days but then some good ones. She doesn't really have a passion for... anything, at this point. I think Phoenix might be a good influence on her, especially since Kit has sort of started helping out mean Slytherins because she's wanting friends.