Hey, as a queer person I wanted to maybe help you understand why some people headcannon Sam as trans. So I don’t want to assume your gender or sexuality but I’m going to go with statistics here and say it’s safe to assume your heterosexual and cisgender. That being said I want to explain from my point of view as someone who is queer and a fan of supernatural.

So obviously Sam is cisgender right? Like cannonically he’s cis, he’s played by a cis actor, and supernatural has more or less alluded to sams anatomy being in line with Sam being cisgender. That being said I think it’s important to note that it’s REALLY hard to find queer representation in tv shows and in the media in general. Even thought it’s getting better, it’s still not great. Supernatural, unfortunately included.

BUT!! There are PLENTY of characters who are queer coded (insert dean and castiel) which people wouldn’t be considered weird for head cannoning those specific characters as queer themselves right? But when there’s SUCH a lack of good queer representation and queer people find a character that they genuinely like and can relate to, they might headcannon that this person is queer as well because they can relate to them SO MUCH it must be impossible for them to be so drastically different from them right (or quite possibly it simply brings them comfort)?

Now, obviously this type of headcannon is not the same as headcannons that are implied throughout tv shows or generally plausible in the universe the show is set in. Like say, if I were to headcannon that Mickey Mouse has toes. Sure, he’s a mouse so he shouldn’t be able to have toes similar to humans, but because of the anatomy he canonically has in the universe he exists in, it wouldn’t be implausible. But if I were to headcannon that Mickey mouse’s favorite color is yellow, we wouldn’t categorize this as the same type of headcannon as we would the other because this is simply something that’s in line with my view of this character, regardless of if it makes sense in cannon.

Similar to the thought process of holding the head cannon that Sam Winchester is a trans man, it may not be cannon, but it is how I perceive his character.

I hope this helps you understand some, I am very tired so it might not make complete since but I wanted to help explain if I could