Perry grew up with Allissa, being her foster brother, although he is quite a bit younger. he's probably 8-10 at the time Jason arrives. Allissa never had any relationship with perry she sort of just ignores him completely as if he isn't there, but he follows her around all the time, so she is very much a role modal for him.
When Allissa leaves Perry takes over her role as the leader of the foragers, to the resentment of the daughter of the leader of the hunters tribe, who feels she should be entitled to that role. Perry imagines he will marry her and has great admiration for her, although she harrases him mercilessly and not in a friendly or loving way.
In Aubyn's version of Destiny of Dreams, Perry and Aubyn hang out together in the forest and spy on Jason and Harris while they're on the beach at Kaar-tal, and follow them up the river spying on them from the forest. Hw is also her forest companion in the spider story, helping take baby spiders to the forest and collecting mates for the bunnies.