Transmasc Shawn, except he grows up in the 80s, with no vocabulary for this in his small city cop household childhood, so he's a tomboy demanding to be called by the male version of his name because it's "cooler" and wants to play with the boys. And his dad always wanted a son to step into his footsteps and trains him and pushes him to sharpen his skills. And both of his parents, wellmeaning but misguided, think it's just a phase.
And he doesn't grow out of it, and puberty just makes it worse. He becomes angry, rebellious. He dates girls, like Abigail, but he knows that he needs to leave to find himself, even though he's still missing the precise vocabulary for it.
And then he leaves for a while, takes odd jobs, travels through America, and meets another trans person for the first time in his life. Maybe at the dance group in Buffalo. Or in rural Argentina. He doesn't tell anyone when he begins to transition. He's somewhere halfway across the continent and he's fully himself for the first time.
And, meanwhile, Gus is doing an internship and he gets introduced to the concept of "sex changes" (it's the late 90s or early 00s) and he has so many questions, enough that the doctor thinks he's mtf, but Gus is just figuring out that his friend was "born in the wrong body" (again, 90s-00s) and that there's solutions for that.
And then Shawn turns up again and he's just. A guy now. Gus takes a second to recognise him on street but when he does he's overjoyed. His father needs time to process it. He's not overtly transphobic, he's just processing that his kid never felt comfortable enough to tell him this. And Shawn tells him he tried telling him, but he didn't know how. And Shawn tells him he always wanted to have a son anyway so what's the problem. And there's a bit of tension between them but Henry realises his son is a lot happier than his daughter.
And then Psych happens and Shawn has to juggle several secrets and identities at once. But it's fun to say things like "when I was a girl scout" and "when I got my first period" and "when I was a little girl" and have everyone laugh because it's so unbelievable to everyone that he's not just joking.