The male lead of the story is named Owen in the American film adaptation Let Me In, and Oskar in the Original Novel, and subsequent Swedish film of the same name. In this article, the name "Oskar" will be used to refer to Oskar/Owen.
Oskar/Owen is a 12 year old boy living with his mother on a dreary housing estate at the city’s edge. His father is not in the picture, which has left him prone to being victimized. The other kids sense this vulnerability, and he is harshly bullied at school. This makes for some uncomfortable situations, as the endless cruelties inflicted on him have left him isolated from other children his age. The psychological toll this abuse has taken manifests itself physically in the fact that he tends to wet himself when he’s frightened.
His isolation leads him to befriend Abby/Eli, since she is alone as well for her own reasons. Eli encourages Oskar to stand up to the bullies and fight back - but this only leads to escalating violence.
Owen also has a very unhealthy habit of constantly eating junk food, just as Oskar had in the book. In Let Me In, Owen's favourite candy is "Now And Laters," and he often sings the jingle to himself, "Eat some now, save some for later." It is seen throughout the movie that he buys numerous quantities of these candies. As Owen rides the train, he quietly sings the jingle to himself, which gives the audience an ominous sense of foreshadowing of what is to come for Owen and Abby.
Although it is often inferred by viewers that Owen is next in line after The Father (Thomas) as part of a cycle of mortal servants who procure blood for Abby, this theory is flawed. Although it is known that Thomas had known Abby since he was a child, it is not known the circumstances of how Abby actually met Thomas, and also unknown are Abby's activities as a vampire prior to meeting Thomas: It is unknown who she was with, if she was with anyone, and if whoever she may have been with had procured blood for her as Thomas later did. Thus, Owen may or may not actually be part of this cycle, if such a cycle even exists.
In the Swedish novel and film, the film ends leaving Oskar's fate ambigious as the American adaption did, but in 2011, Let the Right One In author Lindqvist wrote a short story titled Låt de gamla drömmarna dö ("Let the old dreams die") following what happened to Oskar and Eli after they got off on the train. He wrote it to clarify his intentions with the characters in response to the interpretations that Eli was only preparing Oskar to be her helper all along. After they left the train, Stefan (Not to be confused with Staffan), the train conductor who had asked Oskar for his ticket, witnessed Oskar and Eli exchanging blood, thus afflicting Oskar with the vampiric curse. After reporting what he saw to the police investigating the deaths of Jonny and Jimmy at the bathhouse, Stefan and his wife spent the rest of their lives pursuing Oskar and Eli. Currently, the last information known about Oskar in Eli is that they were spotted in Barcelona during the year 2008.
Although this applies to the book, the characters Eli and Oskar of Let the Right One In and Abby and Owen of Let Me In are technically different characters with different backgrounds, so the scenario of Let the Old Dreams Die may not actually apply to Abby and Owen.
During the events of the story Oskar is a tormented child; going to school is a nightmare as he is bullied horribly by a group of kids. One day, while playing his favorite game "murderer", he meets Eli. The two start to form a bond and become close friends. Oskar loans her his Rubix cube and teaches her the Morse code.