Hi, Riley! I'm Joan, another of the mods here, and I'm excited that you're thinking about joining the game. Sebastian Stan is such a cutie and we've been hoping someone would app a character with him as a PB.
I have characters from almost every district, but the number one person who might have the chance to interact with Jackson is Maizie, whose journal I'm commenting with right now. She's Savannah's (for all intents and purposes) stepdaughter and thus kind of Nathan's pseudo-niece, which gives her a pretty high likelihood of crossing paths with Jackson at some point. Maizie's very outgoing and loves meeting new people, so she'll definitely want to pick Jackson's brain about something or other.
All of my other characters could still possibly interact with Jackson going forward, because travel around Austin is a lot easier now that so many places aren't off limits anymore. >.> Dani is my sometimes judgmental, workaholic lab assistant at the UMCB, Bunny is my Kentucky transplant (Tennessee's neighbor!) who lives in the Greenbelt and works with the livestock and greenhouse they've got out that way, and Kevin is an independent/former Ghoul who's actually pretty laidback and friendly. Whew, and that's all of them!
To echo Justine, let us know if there are any specific questions you have, or any ideas that you'd like to clear before joining. :)