All of the other ghosts we've met are agender (Napstablook, mad dummy, dummy) and Mettaton 's room is very feminine. So there's a headcanon that he's ftm, but at the very least he is agender-to-male
I headcanon him as ftm trans, because his house is very feminine. at the very least, all of the ghosts we know of are agender, so he could be agender-to-male
I usually think of him as a 'gender? Only hot" type of person, like he doesn't put thought into it- All pronouns, all names, he's Mettaton, and who needs arms with legs like these?"
Thats true, he does call mettaton sexy at one point, and has "sexy robot figures" in his room. Maybe I should change it to pan? (since he went on a date with frisk, and thinks mettaton is attractive)