Why, I think it's possible to make any pairing work, if you're really doing your damnedest and have a bit of imagination. The examples I've seen of ToudouxYukio have leaned much towards PWP, with both of them losing core elements of their personalities in the process, and around there I start thinking that no, nah: I would be more interested in reading if the author took the time to explore them as characters and find credible ways for them to come together.
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Oh, which makes me remember something I've always wanted to ask a broader spectrum of people:
characterization in doujinshis/fanart/fanfics where pairings are featured
How important is that to you? Sometimes I've gotten the feeling that it's enough for some fans to just see their favourite characters depicted together, even if they're posing/acting in a way the character wouldn't be likely to do. How much "canonical realism", if I can put it that way, do you require of a work to really like it?