How to do trans headcanons:

“This sequence of events could suggest this character being trans, and I’d like to explore this idea further.”

“I’m trans and headcanoning this character as trans feels pretty good.”

“I don’t really need to explain why I headcanon them, I’m just having fun and using my creative liberties!”

Etc.

How not to:

“This character is trans because I say so, and if you say otherwise you’re a shitty human being.”

“This character is trans, even if it’s not canon it’s canon. If you disagree you’re cishet scum.”

“This character is trans because cis people are boring/I think trans people are so much cooler just because they’re trans. A person’s gender identity totally dictates whether or not they’re worthwhile.”

“Cis people are all scum, everyone is a transwoman/transman!”

This:

“Look how trans this character is!!!”

(That physically hurt my soul to shit out).

-Your friendly neighbourhood trans guy.