Rory and Tresha???
Oh.
Oh wow.
This is the absolute top-tier friendship that I never knew I needed.
They would be best friends instantly. Between being used to living as the sole possessor of the Common Sense Brain Cell™ in their respective families, as well as being perpetually stuck internally screaming at their brother's and best friend's awkward inability to see each other's feelings, and just general dislike of fighting despite fightsy family members, they would have a lot of reasons to get along.
Tresha would love that he's working on becoming an Inter-Folk intermediary through means like diplomacy and making people talk to each other and all those kinds of things. While she is a staunch pacifist, she also recognizes that sometimes you have to protect yourself, so she wouldn't have a problem with his occasional fighting. She would also learn pretty quickly that he has a strict no-kill policy, which would help (except with samontros but that's because they're extremely dangerous to everyone around them, no longer sentient, and too far gone to help). She would also be very curious about his telepathy and how it works.
Rory would appreciate her graciousness to those around her--I mean, she's a pacifist in what eventually becomes a family of military officers, but without letting that get in the way of her relationships-- as well as her kind sternness. He would also love her herb garden. If there were any lingering difficulties, it would vanish pretty quickly if he had any of her cooking.
They would just chill and garden together, probably, share tips on how to deal with the more traumatized of their acquaintances, and (affectionately) smack talk their siblings.