So the foregoing ramble boils down to: I see every sign that the pair of them were well-loved and reasonably happy kids, with not much more than the usual amount of teenage angst, if in a rather unusual situation, and I certainly don't see any signs that they're messed up enough to sleep with each other.

What I really don't understand - though it clearly floats some people's boats, and good luck to them - is fic where adult siblings suddenly start ripping each others' clothes off at moments of tension. It just seems so psychologically unlikely, and makes me think 'You know, I understand being squicked by RPF - I'm squicked by RPF - but how is writing fic full of the Random Surprise Incest supposed to be any better?'

Yeah, word. I suppose the psychologically likely versions would be more likely to a) have LJ come down on them for child pr0n and b) squick the audience or the author, but if my 30-year-old brother started kissing me my reaction would not be to respond in kind, and that's putting it mildly.