[Hider=Relationships]
Obviously these are all just first thoughts and suggestions, I'd love to hear what you think as well, since of course you know your own characters better. 

[@nodogs]
Jack: Billy would have been insistent on staying in her ever shifting circle of friends. I'll leave it to you how she took that. 

[@Salsa Verde]
Mier: Billy would be decent to him, but probably didn't have a lot of interest or common ground to form any real friendship. 

[@banjoanjo]
Sara: if she helped with theater or school talent shows, they would be well acquainted. If I'm reading her right, they both have a people pleasing streak that probably put them together on the same tasks a lot. If you're cool with it, maybe he asked her out once, got rebuffed and kept his distance since. 

[@Prisk]
Hanna: Billy was well liked, but in high school that's not the same as [i]popular[/i], and for the most part they didn't really move in the same circles. They [i]did[/i], however, follow each other on Instagram, and actually still do(though, for his part Billy is only vaguely aware of the fact). 

[@fledermaus]
Genesis: I think they could easily have been "party friends." They'd go out and drink together, but not really because they liked each other. When sober they probably detested each other's company, so I think they'd have had a tempestuous relationship if they had any at all. 

[@Mao Mao]
Lucas: Feel free to reject this, but I think they might have been close until they both abruptly moved out of their respective homes after graduation. Two not-quite-out queer teens gravitating toward each other over illicit smoke breaks. 

[@Eleven]
Freya: Billy would be an ever present face at house parties thrown at her place. They would be as close as she would let them get, so I leave that to you, and we can discuss it at more length if needed. 

[@Odin]
Ben: If someone brings up Benjamin Moore, Billy will be adamant that they must be making him up. 

[@Sweven7]
Conner: I expect they hated each other. I can see Conner jumping in on some jape of Billy's, and simultaneously spoiling the fun, and stealing attention away. 
[/hider]