Abby is a main protagonist from the movie Let Me In.
She is portrayed by Chloë Grace Moretz.
Abby who looks like a 12 year old girl has been nomadic for decades with her caretaker Thomas, whom she poses to be her father. She's a vampire, and he regularly kills humans so she can drink their blood. One day they come to Los Alamos, where Abby moves into a run-down apartment complex.
Abby meets Owen in the playground in front of her new apartment. First she wants him to get out of there and be left alone. She also tells him that they cannot be friends. But over time, the two become friends.
Thomas has in the meantime killed someone and brought their blood to Abby, but lost much of it in an accident. Abby is furious because she is starving because of his incompetence, while Thomas says resignedly that he doesn't know if he's tired of the murder and wants to be caught by the police. Eventually Abby regrets her outburst and treats Thomas a little better.
The following night she meets with Owen again, and they both like each other a little more now. But as soon as Owen has left, Abby is hungry and goes off to kill a man who happens to be passing by and to feed on his blood. When she tells Thomas what she did, he yells angrily at her and leaves the house to hide the body. But this body is found only a few days later.
In the meantime, Owen has given Abby a Morse code so that they can tap through the walls to communicate.
Finally, Abby goes on her first date with Owen. Both have fallen in love, but Abby is reluctant to reveal her true nature to Owen. For his sake, she wears shoes instead of being barefoot, although she doesn't mind the cold. To his delight, she also eats sweets, but has to spit them out shortly afterwards because as a vampire she can only feed on blood. After Owen tells her how much he is bullied and beaten at school, Abby perks him up to fight for himself and to fight back. She also promises to help him if his strength is insufficient.
At one of the next meetings, Owen tells her that this time he fought against the bullys and even injured one of them. Abby then gives him his first kiss.
The night after that, her caretaker Thomas goes out again to get blood for her, but it fails catastrophically and he is caught. In order not to betray her, he disfigured his face with acid before the police can arrest him and he was taken to a hospital. Abby hears what happened over the radio and goes to the hospital, where she poses as Thomas' daughter. When she finds out which room he is in, she flies up. Thomas regrets failing Abby's foraging, and Abby regrets she mistreated him so many times. Thomas offers his blood to Abby and after she sucks his blood, he falls out the window and dies.
That same night, Abby flies to Owen and asks him to invite her. When she comes to his room, she strips naked and lies down in his bed to cuddle with him. Owen asks Abby if she would like to be his girlfriend, but she initially refuses. However, after Owen has assured her that nothing needs to change between them, she accepts. Before she has to leave his apartment shortly after daybreak, she leaves him a romantic poem.
The following night, Owen invites Abby to visit a secret basement room. He wants to offer her a blood pact there, but when Abby sees his blood, she loses control and reveals herself to him as a vampire. She can control herself just enough to spare him and instead attack a woman who is walking her dog outside.
The next day, Owen comes to Abby's apartment. He confronts her, but wants to leave the apartment quickly. When he asks if she'll let him go, or if she'll hurt him too, Abby looks terribly sad and says that she said beforehand that they can't be friends, but lets Owen leave the apartment.
Not long afterwards, she enters his apartment. However, Owen refuses to invite her in, and Abby begins to bleed all over. Startled, Owen now invite her in and gives her a desperate hug. Abby realizes that although Owen was scared of her at first, he really loves her, and she also loves him. She takes a shower there, but has to leave the apartment when Owen's mother walks in.
Owen comes to her apartment shortly afterwards and stays with her for the night. The next morning, however, a police officer (who realized that Abby was behind the series of murders), breaks into Abby's apartment when Abby is sleeping in a dark room; the windows are covered with duct tape to prevent the sunlight from harming her. Owen hides as the policeman enters the room where Abby's in and uncovers her, still sleeping. But as he begins taking off the duct tape from the window, a small stream of sunlight gets in and touches Abby, causing her to awaken as her skin begins to crack.
Owen shouts at him, and the policeman stops and turns to look at him; Abby then leaps onto his back, attacking him and dragging him into the room while leaving a trail of blood behind. Owen closes the door to the room as she begins feeding off of him; moments later, Abby comes out of the room and hugs Owen, her white dress splattered in blood and her mouth drenched in it. After Owen has helped her hide the policeman's body, she kisses him and says that she has to leave now.
One evening after they said goodbye, however, Abby goes to the swimming pool where Owen is, and sees that the bullies are trying to drown or mutilate him. Screaming with anger and indignation, she smashes a window and breaks into the swimming pool, causing the four bullies to look up when they hear her; she brutally kills all four bullies, and keeps her promise to Owen to protect him in doing so.
Shortly afterwards, Owen and Abby leave Los Alamos together; Abby sits in a large suitcase to be protected from the daylight, while Owen sits with the suitcase on a train that leaves in broad daylight. After the conductor has checked Owen and has left, Abby knocks on the inside of the suitcase with Morse code that she loves Owen, and Owen replies the same.
- Abby and Owen are originally based on a novel, the protagonists of which, however, are called Eli and Oskar. Since the film is far enough away from the book, Abby and Owen are different characters, and not identical to those in the book.
- The film has an ambiguous ending about the ultimate fate of Owen. There is both the possibility that he will become Abby's new caretaker or that she will turn him into a vampire. However, the actress who plays Abby said in an interview that Abby really loves Owen, even if she manipulated him a little at the beginning so that he would choose her. In a prequel comic, Abby turned a boy named Jon Dixon into a vampire after they became friends. However, his life as a vampire was very short because a serial killer burned down the house in which Jon, Abby and Thomas were staying. Abby doesn't seem to have a problem turning other humans into vampires if she likes them. Most people believe that Abby will turn Owen into a vampire, partially due to Eli turning Oskar in the sequel/spin-off to the original novel.
- During the film, Abby said several times that she was not a girl. In fact, Eli from the book is a castrated boy who is mistaken for a girl or pretends to be a girl. However, Abby is actually a girl, which is why this phrase doesn't make sense in this context. Unless this statement is interpreted to mean that she is carefully telling Owen that she is not a human. This is supported when she later refers to herself as "nothing".
- The actress tells, Abby is the daughter of a plantation owner, who was born in North America before the USA was founded. From what she says, Abby was born two to three hundred years before the events of the film. The vampire who attacked Abby and turned her into a vampire was her own uncle. A scene was filmed in which one can see this incident. However, this was ultimately deleted from the film because the director was of the opinion that this scene would disturb the flow of the film.