I think Castiel would be extremely accepting of trans people. Imagine somehow someone introduces the concept of Trans people to Cas and Dean is extremely nervous he's gonna say something borderline verbal harassment but he's just like:
"Dean, I have been in vessels of many genders. The fact that a male soul can end up in a female's vessel is of no surprise to me"
And like while Dean's still shocked, Cas ends up going on a rant about how it is normal for some other species to just swap their biological gender or to have the attributes of both sexes.









