“I wanted to kill you tonight,” Angel says to Buffy in “Angel” (1-7), as he’s explaining not only his life story to her, but also the truth about his nature. As Angel’s dialogue indicates in that same scene, the Buffy ethos equates a soul with humanity, with a conscience, with the ability to experience remorse and guilt. Prior to regaining his soul via the infamous gypsy curse, Angel was (as Giles describes him when first researching Angel’s past) “a vicious, violent killer.” Two seasons later, when Angel tries to twelve-step the rogue Slayer Faith while she’s chained to his wall in “Enemies” (3-17), he recalls the pre-soul clarity and exhilaration of killing without remorse, which he remembers as an addictive pleasure. And when Angel loses his soul in season two’s “Innocence” (2-14) and spends the rest of the year tormenting Buffy, killing innocent people, and wreaking havoc in Sunnydale, we see for ourselves just how evil Angel is without a soul.

But what’s interesting about Angel is not how evil he is when he’s bad . . . but rather, how evil he is when he’s “good.”

“I wanted to kill you tonight,” says the good version of Angel in that season-one episode, the version of Angel whom Buffy invites into her home, trusts with her life, and grows to love. This is the kind of stark, unmitigated impulse that can (and often does) seize Angel. Many desires and instincts just like this one live inside his skin, and he  …