The novel’s title, Let the Right One In, is thematic of many decisions that characters must make throughout the narrative. These decisions arise when characters deal with perceptions of what it means to be monstrous and/or human. The title also alludes to a common trope in vampire fiction, where vampires cannot enter a dwelling unless he or she receives an invitation. There are many variations on this theme, and the question of whether Eli is “the right one” for Oskar comes to the fore many times in the novel, and the answer lies in Eli’s ability to bring out the best in Oskar and vice versa.

One of the most memorable instances of letting the wrong one in takes place with Virginia’s character. Right before Eli attacks and bites Virginia, Virginia leaves a bar in anger. Virginia is angry because she doesn’t feel that her lover, Lacke, truly appreciates her. As she walks toward her doom, sobbing, Virginia says, “Let a person in and he hurts you” (220). For Virginia, Lacke isn’t a person deserving an invitation to her love, her heart. Ironically, a few minutes after uttering the above-mentioned quote, Eli attacks Virginia.