spicy headcanons.
klaus is insatiable; thanks to having nearly infinite stamina, he could quite literally go all day if he wanted. he typically only stops or takes a break if his partner needs to . . . and also because ig he has actual things to be doing, unfortunately.
he is very dedicated to his partner's pleasure, and is basically a service top (believe it or not). if he's with a committed partner, he's this way because he genuinely enjoys pleasuring them and watching them get off (especially at his hands) is satisfying to him - sometimes even more than the act itself. if he's with a hookup, it's more an ego thing - to him, it's shameful for a man to leave a sexual encounter without thoroughly pleasuring their partner and he would find it embarrassing if they didn't finish at least a couple times.
he's an obsessive eater, and far prefers giving head to receiving it. again, it's exceptionally satisfying to him to watch his partner come undone under him, and he's the type to hold their hips down and keep going until they're nearly crying from overstimulation. an any time, any place situation for him; all his partner has to do is ask him to and he'll be telling them to pull down their pants and he'll dive in.
you'll probably gasp with shock at this one, but he's almost exclusively dominant. his obsessive need for control makes him unwilling to submit 99% of the time, and it's very difficult to find someone who'll be that 1% exception. being dominant and having another submit to him is a big part of being intimate to him, but the inverse (aka him giving up control and submitting) could be just as impactful with the right person.
another obvious one, but he's a constant biter and loves leaving marks everywhere. the more excited he gets, the more mouthy he gets, and he will bite bite bite! this is reciprocal, as he enjoys being marked by his partner, even if the bites heal quickly.
he enjoys seeing his s/o in lingerie, and more specifically, things he purchased and chose for them. this also includes certain jewelry, such as chokers or rings (or piercings, if they're brave enough and down for that), anything that marks them as his. he likes picking out what lingerie they wear, when they wear it, having them take pieces of it off in public to give to him, etc. he also gains satisfaction from dressing them in general, even outside of lingerie.
i feel like this is already too long, so i'll speed run other k.inks: bloodsharing, dom/sub dynamics, primal themes (chasing, claiming, etc), choking, general manhandling, c.ockwarming, watching his partner, giving / receiving praise, worshipping / being worshipped, etc.