Reincarnation: Major theme of the episode. Melissa channels her past lives and Mulder finds out about his past lives under hypnosis.
Reincarnation Romance: Mulder, under hypnosis, recounts that he, his sister, Scully, and Cancer Man have been reincarnated into each other's lives over several lifetimes and are always related, and Cancer Man is always evil. Mulder's supposed soul-mate-in-every-life is a woman named Melissa who also channels a guy called Sidney and Lily, a little girl. It's kind of wierd that they are supposed to be that close all the time, and here she's one off character who's hard to relate to.
Would Hurt a Child: From Melissa's testimony, Vernon was quite an abusive person who sadistically hurt a child.