My comment is copied here:
What appeals to you about the character of Spike?
I fell in love with Spike just about the time that battered boot swung out of the Desoto and landed on Sunnydale tarmac. I adored the way he was so obviously a different vampire from the others, even Angel, in that he truly loved Drusilla, and took so much care over her welfare. That and the fact that he was so damn pretty, even in gameface.
He's a vampire who loves deeply and completely, even obsessively, and because he is loyal, in his own twisted way. He needs someone to take care of, and he's never in all his 100+ years been alone, and IMO Xander so badly needs 'taking care of' that they are just perfect together.
What slash scenarios/pairings do you most enjoy with Spike and why?
As I said above, Spike and Xander. Spike needs someone to take care of, and Xander so needs someone to take care of him, protect him from himself when he's being a demon magnet, and rebuild some of his self-esteem which seems to have been trampled into dust by his super-special friends: the Slayer, two witches, an ex-vengeance demon, a reformed Chaos Mage. He's the only 'normal' one of the lot and yet he keeps plugging away and getting hurt.
Plus, they look really really pretty together. ;op
Why is he so good for slashing?
Is it that smudged eyeliner? The chipped nailpolish? The love of bleach? The long swishy leather coat? Or is it that 'you know you wanna' look in those eyes? The cocky cant of his hips? The complete flamboyance of his every move? I don't honestly know. But he looks small and fragile and pretty, and the combination of that with demon strength and the never-gonna-age twist and you have a very pretty boy who's lived too long to confine himself to one side of the street.