You know, aside from my whole "he should have remained dead" thing (and even that is complicated by the fact that I love the Angel/Spike interaction in AtS season5), I think Spike became a favorite of mine. A pet character. Hehe. I wanna make Spike my pet.
Anywho... before my brain went off on a funny Illyria quoting tangent, I was attempting to say that Spike's character development was one of the most compelling aspects of the show for me. My mind, when it is not otherwise engaged in leering at Giles, is most often drawn toward Spike. He's exactly the kind of character that I love: he's complex, hopelessly flawed, funny, and brimming with contradiction. My favorite aspect of Spike's character, the part that I have often confessed to inspiring in me a certain degree of writer lust/jealousy, is how he can vacillate between extremes without seeming out of character. The episode that made me fall in love with him was Intervention; any character who can, in the same episode and without breaking character, defile and degrade Buffy with the Buffybot and yet also suffer torture at the hands of a God for the same woman that he dehumanized is just plain amazing. He's always been like that. Even in School Hard, his tender love for Dru was juxtaposed with the image of him as a deadly predator. Watching Spike struggle with this inner duality and grow into the champion he became in Chosen was beautiful. I loved the ups, the downs, and everything in-between. Spike's growth was, in keeping with his character, epic in scale and poetic in tone and execution. He is quite possibly the most meticulously and consistently well written character on the show.
I take it back. It's not lust; I'm in writer love. I *wish* I could write a character as complex and beautiful as Spike!