Well, looking around, Walker generally isn't the person for crushes. However, I had the thought that maybe Walker was the potential friend Jorge was holding weed for? 

And I also saw Walker being friends with Duncan. Especially if he was accidentally smashing pencil sharpeners in school. He thinks that's totally rad.

For Tristan, maybe she and Walker know each other through her bestie Jayce. Depends on what kinda guy Jayce is. Either way, Walker plays guitar, too. They could have jammed together at some point.