I thought this was gonna be a porn with plot because of that crotch tattoo (which ain't a bad thing considering how much of a degenerate I am for my taste), but the plot and character development are strong in this one!!!!
seme is a damn ISTP I'm telling you. I'M FUCKING TELLING YOU HERE. It's nice to see his character development. Some people will hate on him because it looks like the typical "cool, aloof, I'll rape you" trope, but no. He has reasons for everything he did (and it's not just yaoi logic, well, except the maiden part lol), but he goes about it in a way he can solely rely on himself. I'm saying this author is doing a good job for this character.
As for uke, I think he's ESFJ or ISFJ, which is a nice match for our seme. It's like he's teaching a younger brother minus the sex or sth.
Dear Sister, I've Become a Blessed Maiden