You can't not appreciate an episode like this that provides such a rich back story for one of the show's most popular characters. After Buffy is nearly killed by a random vampire, she becomes obsessed with trying to figure out exactly what it was that led to the other slayers' deaths. How did they slip up? What mistakes did they make? Then she realizes that she has a primary source available to her, being on friendly terms with a vampire who happened to have killed two previous slayers himself. What follows is a character study that explores not just the two slayers that Spike came into contact with, but Spike himself. The juxtaposition between him and William the Bloody is jarring but somehow manages to answer a lot of unasked questions and blends in fluidly with everything else the audience knows about the character.