That’s just your headcanon for a character. In real life, lots of quiet people turn out to be complete freaks in bed and lots of gruff macho dudes turn out to be subs. As long as Promare’s creators don’t confirm anything, fans are free to make up whatever they think a character would act like in the bedroom. Maybe he’s a total loser virgin and he’ll nut in 10 seconds while crying the whole time? Who fucking knows. Let other people make their porn in peace.