In the context of Selina Mandrake - The Slayer, John and Alan are two vampires from England, who are the first demons to be slain by Selina Mandrake. They approach Selina, while she is sitting in the library doing her mathematics homework, and in a friendly manner tell her that she is supposed to slay them. Selina says she has no intention of slaying them herself, and they agree to be on good terms. After discussing various elements of popular American and British popular culture, they try to emulate the suicide squad skit from Monty Python‘s Life of Brian , and they stab themselves to death using Selina's unsharpened pencils, gasping “OH NO! WE HAVE BEEN SLAIN BY BUFFY MAGEIA, THE SLAYER.” and evaporating into dust, which Selina later needs to clean.
Later on, The Guide tells Selina that John and Alan were “notoriously deadly and dangerous”, but that the worst is ahead of her.