Dexter had an affair with Lila, leading to his breakup with Rita Bennett but ultimately he returned to Rita with Lila out of the picture. Officially, she is the Second Main Antagonist. She is the first antagonist to kill a main character, James Doakes (the second being Arthur Mitchell).
Lila appears to be a fun-loving, compassionate person. However, as the season drags on it is revealed that Lila is in fact a borderline personality who frequents support groups in an attempt to feel emotions she is otherwise incapable of. Lila was a compulsive arsonist, and was responsible for at least four fires:
- She set fire to her ex-boyfriend's house and ended up killing him. Mentioned in The Dark Defender.
- She set her loft on fire to get sympathy from Dexter, when they were drifting apart. Occurred in That Night, a Forest Grew.
- She caused a cabin to explode in the Everglades, killing Sargeant Doakes. Occurred in The British Invasion.
- She again set her loft on fire with Astor, Cody and Dexter inside, in an attempt to kill them all. Occurred in The British Invasion.
She also confessed to Dexter that she went sober after unintentionally killing her ex-boyfriend by setting his house on fire while he was inside, passed out on drugs. It is unknown whether or not this actually happened. She immediately sees through Dexter's "mask," and does not get fazed by his dark personality, but she does not learn the truth about him until the end of Season 2, at which point, she is obsessed with him, believing him to be her soul mate.
Lila's dark personality, pale skin, British heritage as well as her sociopathic tendencies and her being able to see Dexter for what he is a deliberate contrast to Rita's bright personality, tanned skin, American heritage, respect for the law, love for her children and inability to see Dexter's dark passenger. Lila acts almost as the love interest for the Dark Passenger inside of Dexter, giving it confidence and telling Dexter to accept it while Dexter's love for Rita acts as the catalyst for Dexter's rejection of his Dark Passenger and his eventual shaping into something more human and sane than what the Passenger wants him to be.
Although it is never mentioned, it can be deduced that she is from England, possibly London. This is clear from her accent, the threat of deportation from Debra (meaning she is from another country outside the USA) and the fact that she mentions in That Night a Forest Grew that 'Everybody walks in London... of course they're usually walking to the pub!' Also, the last episode of season two is called "British Invasion".
Lila is introduced as a recovering drug addict when Dexter is sent to a Narcotics Anonymous meeting by Rita. She finds an immediate interest in Dexter and sees through his facade, sensing that he is hiding his true emotions. As Dexter becomes more immersed in the drug recovery program, she becomes his narcotics sponsor and they begin to spend more time together much to Rita's chagrin. As Dexter seeks a way to control his "Dark Passenger" he cryptically asks Lila for advice, pretending that his problem is a drug addiction. By her advice, they set out on a road trip to seek some closure from his past and the person who turned him into who he is, the man who killed his mother, Santos Jimenez . However, as Dexter loses his control and is about to kill Jimenez in vengeance, he is calmed down by Lila over the phone who was convinced he was shooting himself with heroin again due to the stress of meeting his mother's murderer. This experience brings Dexter and Lila closer together and Dexter becomes convinced that Lila can help him manage his urges to kill. On their return however, Rita discovers Dexter's secret road trip when Lila accidentally summarizes their trip over the answering machine. Assuming that Dexter and Lila had sex on their trip, Rita dumps Dexter. Out of stress and rage over the breakup, Dexter visits Lila's apartment only to end up sleeping with her for real due to the sexual tension and begins a romantic relationship with her. The relationship does not last long however, when Lila begins to feel that Dexter is drifting apart from her (when in reality, he was just pre-occupied with the Bay Harbor Butcher case). This drives her to reveal her hidden insanity: she sets fire to her own loft, helps Santos Jimenez attack Dexter (believing that she and Dexter are closest in times of crisis), and breaks into Rita's house, afraid that Dexter might have gotten back together with her. These action convinces that Lila is too unstable to pursue a relationship with and Dexter immediately ends their affair.In retaliation, Lila begins dating Dexter's co-worker, Angel Batista. When she realizes this has no effect over Dexter, she has rough sex with Angel Batista and then accuses him of rape (She had taken Rohypnol immediately after sex so it would look like he had drugged her) in an attempt to gain Dexter's sympathy. Enraged, Debra runs a background check and discovers Lila's real surname (West) and the fact that she has been illegally living in the United States on an expired visa. Debra then confronts her and demands that she leave the country or be deported. Lila, following Dexter and watching him on his boat with Rita, Astor and Cody, breaks into his van, takes his GPS device and finds the address for Jimenez's cabin. Arriving at the cabin, she finds Doakes caged inside and, upon learning from him that Dexter is the Bay Harbor Butcher, decides to protect Dexter and ignites propane canisters inside the cabin, killing Doakes.
After Dexter discovers that Lila killed Doakes he meets with her to thank her for the intervention and offers her a chance to run away, when in reality he meant to kill her in a remote location. However, when she discovers that Dexter meant to kill her she abducts Astor and Cody as revenge. Although Dexter tracks them down, Lila traps them inside her loft and sets it ablaze saying they "Could have had it all". Fortunately, Dexter and the kids narrowly escape, and Lila flees Miami.While living in Paris, Lila checks her mail and discovers a postcard from Miami with Doakes' picture on the back. Dexter, who was in the room the entire time, injects Lila with a spinal epidural (so he can speak his peace to her while also ensuring that her death is painless) and lays her down on the couch. Lila pleads for her life and tells him that she killed Doakes and tried to get rid of the children for Dexter's sake. Dexter thanks her for helping him embrace what he is, and then stabs her through the heart. He wraps her corpse in a plastic clothing bag.
- Officially she is the second main antagonist and the first female antagonist, the second one being Maria LaGuerta. She is the first antagonist to be from a foreign country as well as the first antagonist to be a threat to Astor and Cody.
- She is the first main antagonist of the series who does not have a presence in all episodes of the season, with her being absent in the first two episodes of Season 2; while Season 1's Brian Moser did not appear in all of the first season's episodes, he was still a central threat from the season premiere to the season final.