Or, you know, just *one* pairing, since this turned out to be fifty times longer than I intended and took me three days to write.
Giles/Xander: I find this pairing a hard sell. I get zero subtext or sizzle off them. I don't even see a deeply concerned paternalism on Giles's part--not like we see him demonstrate toward Buffy or Willow. It'd be easy to "cheat" given the nature of the Jossverse and say that the only way they'd hook up is with the help of magic. Heh. In fact, thinking about such an unlikely pairing makes my mind go immediately to all the staple clichés of slash fiction: Giles and Xander in prison together, Giles and Xander Must Have Sex or Die!, Giles and Xander go undercover as big gay lovers. Not that any of those really work for me here, but it's amazing how many I can roll off the top of my head. And what I was really trying for with this meme is to imagine a scenario stemming directly from the unique personalities of two characters, and how those personalities mesh. More like: what would Joss do if he wanted to make canon go there?
Looking at it that way, Giles/Xander would probably happen in S4, when both of them were adrift. You'd have to write Anya out of the picture. Give them a shared and stronger jealousy of Riley; a sense of displacement, uselessness to Buffy. So they'd hang out more, finding common ground that wasn't previously obvious--ooh, Giles takes Xander on as an unofficial watcher apprentice. Xander comes out as gay; you can't really avoid that prerequisite, so we should just go there boldly. And of course he'd crush on Giles, because shows always draw from their core cast when it comes to setting up romances and relationship plottiness. It would only slowly dawn on Giles what all of Xander's fumbling meant, and he'd become standoffish, nervous. And one evening Xander would surprise him by being there in his apartment when he comes home, cooking him dinner. Giles looks like a deer in headlights, they bumble through a heart-to-heart; Giles has previously confessed in a careful, euphemism-laden way to having a bi-friendly past, but now he expresses uninterest in Xander--which baffles Xander, because to his logical mind, if you're *that way*, wouldn't you be interested in the nearest other guy who is also *that way*? Giles gives him the hairy eyeball, amazed at this line of reasoning. They come to an understanding and Xander starts dating someone his own age, but one brush with death later--Xander's--Giles is grabbing and kissing him. Shocked at himself, he retreats, but Xander pursues, and you get him taking a deep breath and making a gutsy emotional play, kind of like the closing Xander-Anya scene of "Into the Woods" or the Willow-Tara of "New Moon Rising," and you get this sweetly downplayed May-September romance which takes place mostly offscreen and slowly trickles into the consciousness of the others via subtle cues--Xander always being at Giles's and knowing where things are in the kitchen, bringing out a bowl for the pretzels during a Scooby meeting; and their body language would be careful. You'd see their intimacy more in how they don't look at each other than in how they do. Et cetera.
And Anthony Stewart Head and Nicholas Brendon would make the cover of the Advocate together!
Anyway. I was going to pull all sorts of crazy or challenging ships out of a hat--Andrew/Faith, Angel/Gunn, Buffy/Giles, Buffy/Willow, Riley/Anyone But Buffy, Dawn/Spike/Xander--and try to rationalize them, and of course I realize that one fan's "crazy or challenging" is another fan's "well of course" but I'm just leaving that one alone. And I think I'm done with this lunacy for the moment.