I've been thinking about standard flavor DirkDave where Dirk is actually the inexperienced one. It makes sense in a way, after all Dirk probably had nothing but the Internet and his hand(and maybe some household objects, sex toys if he's really lucky), whereas Dave might have experienced way too much way too early. I think Dirk would have the theory down, he would understand what he's supposed to do and why, but the first time he and Dave have sex Dirk just feels so clunky and awkward compared to Dave who could probably do this stuff in his sleep.
Dirk trying to deepthroat Dave for the first time and gagging on it and having to pull back, Dave sliding his fingers into Dirk's hair so that Dave can guide him back down a little slower and get him into a better position. I think the thought of "maybe this is what Bro got out of it with me" would cross his mind at least once while teaching Dirk to actually have sex, and I think he would feel absolutely revolted at that feeling, at the fact that ok sure Dave's enjoyment is a thing of affection while Bro's was probably a thing of control, but it's still the same thought pattern. It's still enjoying watching someone under you struggle and fail to do the right thing, still enjoying putting a correction in place, still enjoying the obedience that follows. For all Dave knows, Bro could have thought it was a thing of affection too.
It's mostly a one-sided crash out. Dirk would certainly feel bad that he didn't actually have all of the strategies down, that his first time with Dave was a mess because Dave was just so much better at sex than Dirk was. However, Dirk doesn't have any serious morality issues attached to it, just a bit of self loathing at not having been prepared enough. I do think that that self loathing would cloud Dirk's understanding of the situation, though. I don't think Dirk would notice just how much Dave enjoyed teaching Dirk new tricks. I don't think Dirk noticing that would have really helped though, it would have tipped the issue in the other direction; Dirk would feel that he shouldn't have learned anything about sex, that he should have completely abstained from masturbation, that he should have let Dave teach him everything so that Dave could get the experience of teaching Dirk as many times as possible. (It's definitely a bit of his leftover complex with a!Dave. Dirk just still can't shake the mindset of wanting to be the perfect little brother for a!Dave, even though he's long since given up hope of ever meeting a!Dave.)
