Becca the Vampire Slayer

When young Benjamin starts questioning their gender, they also start to gain inhuman strength. They can lift the couch up one handed without breaking a sweat, be the fastest on the track, punch bullies across the hallway, but why? Then, Anthony Giles informs her that she is the first male to be chosen as the next Slayer and at that point, she's got some news for him: She's trans. And he's totally cool with it, and discovers that being a Slayer is a power so innate, that it even ties to one's gender identity and perhaps even ascends gender binary altogether.