Caleb was so dark. Castle is all light and (mostly) fluffy though he has his dark moments.

One of these days I'm going to write something set during 'Helpless', I just need to do an episode re-watch before tackling it and I have no idea when I'll have time.

Buffy was such a great show because of all the great characters, not just the good guys either, even the Big Bads (and the smaller bads dotted throughout each season) were interesting characters in their own right.