Fool For Love/Darla
It's Spike's episode this week as he tells Buffy how he killed two slayers, and we learn his history through flashbacks. He gets more Psych 101 with Buffy than she probably expected, but we learn a lot about his motivations for becoming William the Bloody and the origins of his Buffy obsession. On Angel, Spike's story overlaps with Darla's, who is struggling with her human existence.