Well, I can get cynical here. If it weren't for how Twilight was written, Spike would be on my list of candidates for Twilight. In fact, I'd think that would be *very* interesting. But Twilight doesn't sound at all like Spike. Nor does his MO remotely resonate with anything we know about Spike. But here's the cynical note: Joss DOES cheat when it comes to getting "plot twists" (see Spike's soul quest). So that door is open, even though it should be flat not possible.