Maria LaGuerta

Lieutenant María LaGuerta is a tough, determined woman in command of the Homicide division. At the series' beginning, she had a sincere dislike for Debra which in later series has all but disappeared.^[2] In the first season, she made no secret of her attraction to Dexter, with whom she flirted constantly, to his discomfort. After the first season, however, it is suggested that she sees him more as a good friend. At the end of the first season, she is removed from command.^[3]
She returns to her old job once the new Lieutenant, Esme Pascal, proves to be unstable (a state LaGuerta intentionally worsens by having an affair with Pascal's fiancé).^[4] When her friend and former partner and lover, James Doakes, becomes the prime suspect in the Bay Harbor Butcher case, she tries to clear his name. However, Doakes is found dead in a seemingly accidental explosion along with the body of drug dealer Jose Garza, and the case is closed. As she recovers from the trauma of Doakes' death, she leads an investigation into the murder of Oscar Prado, the brother of her ex-boyfriend, Miguel Prado. She also develops a close relationship with defense attorney Ellen Wolf, and is devastated when Wolf is found murdered. After Miguel's own murder (ostensibly at the hands of The Skinner, but in reality by Dexter), she wants to find admissible evidence to prove he killed Wolf, but Dexter is able to convince her that doing so would only hurt Miguel's family and the Cuban community, and that even then there is a high chance that nothing will be proved. Reluctantly, LaGuerta drops it.
At the start of Season 4, she is shown to be romantically involved with Angel. They keep their relationship hidden from the rest of the homicide department, aside from Dexter, who both Angel and LaGuerta confide in. Their relationship hits a roadblock when she tells their superiors about their relationship so that it cannot be used against them during a trial. The consequence of her disclosure is a threat of reassignment; either Angel or LaGuerta will have to move out of Homicide. Deciding that their jobs are integral parts of who they both are, the two decide to end their relationship, and sign affidavits to that effect. Staying away from each other does not prove easy however, and they begin having secret liaisons once more. In order to circumvent a reprimand from higher up, and also as a result of their deepening feelings for one another, they secretly get married with Dexter as witness.
LaGuerta and Batista divorce in between seasons 5 and 6.
In season 6, Captain Matthews is promoted to deputy chief and LaGuerta is promoted to fill Matthews' position. It was later disclosed that LaGuerta had blackmailed Matthews in order to become the captain. LaGuerta wanted to install Angel Batista, whom she can trust, to be the new lieutenant of homicide division, but as a payback to LaGuerta, Matthews appoints Debra Morgan to be the new lieutenant instead. Later in Season 6, when Matthews was involved in a prostitute's overdose death, LaGuerta used Debra Morgan to keep the case alive and eventually leaked the information to the police chief, who forced Matthews to retire. It was implied LaGuerta would become the next deputy chief.
At the onset of Season 7, LaGuerta finds the blood slide of Travis Marshall at the scene of his death. Remembering that this is the MO of the Bay Harbor Butcher, she then launches an independent investigation as to whether the Butcher was still active and James Doakes was innocent. In Season 7's finale, LaGuerta finds out Dexter is the Bay harbor Butcher, and arrests him. Dexter, anticipating LaGuerta's move, made it look as though she was framing him as the Butcher. LaGuerta then finds more evidence of Dexter and Debra's involvement in the death of Travis. She is eventually killed by Debra, with a shot to the chest, who finds her and Dexter in a shipping container as Dexter was trying to frame her for the murder of the killer of Dexter's mother, Hector Estrada.

Rita Bennet

Rita Bennett was Dexter's girlfriend and later wife. Rita is portrayed as a mother, who is slowly recovering from being physically abused by her ex-husband, Paul, and having difficulties maintaining a sexual relationship. Rita tentatively starts a relationship with Dexter, while remaining unaware of his extra-curricular activities. In season two, Rita's relationship with Dexter becomes troubled. After discovering that Dexter framed her ex-husband Paul with drug abuse, she suspects that Dexter owned the drugs himself. She pushes him into Narcotics Anonymous, but begins to suspect that he is having an affair with his sponsor, Lila, and breaks up with him. In anguish, Dexter turns to Lila, and consummates what had before been a platonic relationship. After Dexter lies to Lila about working late (he had gone to kill Jimenez), Lila breaks into Rita's house, afraid that they had rekindled their relationship. Angered, Dexter breaks up with her. His breakup with Lila, his love for Rita and her children, and his sincere regret over what he had done convinces Rita to start dating him again.
In season 3, Rita suddenly discovers that she is pregnant with Dexter's baby. Believing that being a parent is one of her main achievements, Rita decides to keep the baby, and leaves Dexter's role in the child's life entirely up to him. After much deliberation, Dexter decides (with Debra's help) that he will be there for the child and Rita accepts his marriage proposal. Rita loses her job when she is rude to a customer, but gets back on her feet by working as an assistant to Sylvia Prado.
After the baby, Harrison, is born, Rita and Dexter move into a house together in the suburbs. Rita begins to notice a pattern of lies from Dexter, including deceiving her about the concussion he suffered in the car accident and the ownership of his old apartment. Rita and Dexter then go to a marriage counselor, who allows them to sort out their problems and instigates peace between them. However, their neighbor, Elliot, begins to fall for Rita, kissing her and pointing out that Dexter is never home. Though she initially kisses him back, she quickly ends it before something begins. In the Season 4 finale, Rita is murdered by the Trinity Killer, leaving her son Harrison sitting in a pool of her blood.

Harry Morgan

Harry Morgan is Dexter's adoptive father. When alive, he was a detective and highly-respected member of the Miami Police Department. In the course of a high-stakes drug case, Harry began an illicit relationship with Laura Moser, Dexter's biological mother, to gather information and evidence on the drug lords in question. Laura was discovered and made an example of; she and three others were executed with chainsaws in a shipping container. Her sons, Brian and Dexter, were left in the container for several days^{[citation needed]} until Harry and a police team recovered them. Harry adopted Dexter, while Brian was sent into foster care.
At first, Harry attempted to manage Dexter's violent urges by only allowing him to kill animals, but he eventually came to the conclusion that Dexter's pathology could not be repressed, only controlled: Harry decided to train the boy as a vigilante, to hunt and kill murderers without leaving any clues. Dexter prized these lessons as a means to fulfill his desires with his father's approval, dubbing them the "Code of Harry". Harry's relationship with his biological daughter Debra, meanwhile, was more complicated. She craved her father's approval, but felt that he favored Dexter.
When Dexter was 19, Harry fell seriously ill and gave Dexter "permission" to kill one of his nurses, who was intentionally poisoning him with morphine. A year later, when Juan Rinez, a pimp who was murdering prostitutes, was released due to a faulty search warrant, Harry lost his temper and told Dexter he was right in training him. When Dexter killed Rinez, Harry was horrified by the way Dexter proudly showed him the pimp's dismembered body. Harry committed suicide a few days later, by overdosing on his medication.

DEBRA MORGAN

Debra Morgan (known as Deborah Morgan in the book) is the younger foster sister of Dexter and biological child of Harry Morgan. Debra believed that she truly knew her father, but is unaware of the secrets he kept, especially concerning Dexter (whom she sees as a true brother). Inspired by their father's legendary police career, Debra joined the police and desperately yearned to become a homicide detective. Initially assigned to Vice, she was transferred to Homicide at the start of the first season. Being new to the job and very insecure, she largely relied on Dexter's expertise on murderers to solve difficult cases. Debra met Rudy Cooper, who unknown to her is the Ice Truck Killer using her to get close to Dexter. She falls in love with him, but is later kidnapped by him in order to be able to reveal himself to Dexter. She is bound to a table in the same manner that Dexter kills his victims, while Dexter and Brian discuss her fate. In the show, she is unconscious, but in Darkly Dreaming Dexter, she is awake and finds out that her brother is a killer. Debra is severely affected by Rudy's betrayal; she moves in with Dexter for fear of being alone.
Throughout the second season, Debra stays in her brother's apartment as she deals with the trauma of what happened, but leaves his apartment in a mess. Debra is a key member of the police task force in charge of finding the Bay Harbor Butcher, who is secretly Dexter. She falls for an older man, Frank Lundy, the FBI agent in charge of the case, all the while improving her ability on the job. By the end of Season 2, Debra has recovered from the trauma of the Ice Truck Killer, confident as an officer, and is determined to get her detective shield.
In Season 3, Debra has had her hair cut to shoulder length, has "sworn off men, liquor and smokes" and is even more determined to get her silver detective shield. She is working with a new partner, Detective Quinn, but has been approached by an Internal Affairs officer who tells her that her partner is being investigated as a dirty cop, but she refuses to help them. She was originally part of the team investigating the murder of Miguel Prado's brother, Oscar, but because of her lack of tact and people skills she was removed from the case by newly promoted Angel Batista; however, the case she had been assigned (the murder of a young woman) was eventually found to have been connected to the Skinner case, which she solved with the help of Anton, a C.I. whom she started dating after saving his life from the Skinner. Because of her success on the Skinner case, she was promoted to detective at the end of the season.
She is known to have a very foul mouth, and she hardly speaks a sentence without swearing. This has nearly gotten her into trouble, as she often speaks profanely to her superiors, only to realize a few seconds after. It finally got her into trouble in the third season, as a poorly-timed public comment caused her to be kicked off the Freebo case. She is also known for being easily angered and frustrated by suspects. Though she is frustrated at Dexter's inability to open up to her, she has defended him on more than one occasion.
A conversation between her and Dexter leads to her finding out that her father slept with one of his confidential informants. She investigates the files on Harry's informants and interviews some of them, hoping to find the one with whom Harry had an affair. One of the files is shown to be that of Laura Moser. Also during this time, her relationship with Anton had been breaking, especially now that he had secured a gig in the city instead of on a cruise ship. Also, Frank Lundy returns to Miami to hunt the Trinity Killer, and Debra once again becomes involved with Lundy. Soon, both she and Lundy are shot by an unknown assailant suspected to be the Vacation Killers. In her hospital bed, she confesses to Anton that she slept with Lundy, prompting him to leave her. Lundy dies, and she eventually concludes that the Trinity Killer must have been the shooter. As a result, Debra opens an investigation on the Trinity Killer. However, it is later determined that Trinity could not have been the shooter, since her wounds from the bullet were at a horizontal line, therefore someone of Masuka's height had to be the shooter. During a Thanksgiving dinner Debra remembers a conversation she had with Christine Hill and realizes Hill has knowledge of the shooting that no one outside the police department should possess. This leads Debra to believe that she was the shooter. This is backed up later when it is revealed that Hill is the daughter of Trinity. Hill later confesses to Debra that she was the shooter, and proceeds to shoot herself in the head. Due to her solving the Lundy killing, Debra restarts her search for Harry's C.I. mistress, and finds out about Laura Moser, and the fact that Dexter and the Ice Truck Killer were brothers.

DEXTER

Dexter "Dex" Morgan (born Moser) is the main character and narrator of the series. Dexter is a forensics expert and blood spatter analyst employed by the Miami Metro Police Department, but has a double life as a serial killer. As young boys, he and his older brother Brian witnessed the murder of their mother, Laura Moser, and were left for two days in a shipping container filled with blood. The incident left them psychologically scarred. Soon afterwards, Dexter was adopted by Harry Morgan, who hoped to help repress his memory of the death of his mother. However, he soon realized that Dexter had an insatiable urge to kill that would begin to intensify. Harry, frustrated with the number of people who avoided justice, decided to train Dexter as a killer who would target and dispatch other murderers.
Dexter considers himself emotionally divorced from the rest of humanity; in his narration, he often refers to "humans" as if he is not one of them. Dexter makes frequent references to an internal feeling of emptiness, leading to several attempts in his youth to "feel alive". Dexter claims to have no feelings or conscience and that all of his emotional responses are part of a well-rehearsed act to conceal his true nature. In the first season of the television series he had no interest in romance or sex; this changed when he became involved with Lila in the second season. He initially considered his relationship with Rita to be part of his disguise. However, by the end of the fourth season, Dexter had fully evolved into a family man and wished to rid himself of his self-titled "Dark Passenger".
There are chinks in Dexter's emotional armour, however. He acknowledges loyalty to family, particularly his now-deceased, adoptive father, stating "If I were capable of love, how I would have loved Harry."^{[citation needed]} Since Harry's death, Dexter's only family has been his sister, Debra Morgan, Harry's biological daughter. At the end of the first novel, Dexter admits that he could not hurt Debra or allow Brian to harm her because he is "fond of her".
Dexter likes children.^{[citation needed]} The flip side of this affection is that Dexter is particularly wrathful when his victims prey on children.^{[citation needed]} In the book Dearly Devoted Dexter, Dexter realized that Rita's son Cody was showing the same signs of sociopathy as Dexter had at that age, and looked forward to providing him with "guidance" similar to that which Harry provided him. Cody's perceived sociopathy has not been shown in the television series.
This also gives him a reason to continue his relationship with Rita, to whom (as of Dearly Devoted Dexter) he is engaged because of a misunderstanding. At the beginning of the third book, Dexter in the Dark, it is revealed that Cody is not the only one with dark impulses, as Astor too pressures Dexter to teach her. Dexter comes to accept his role as a stepfather to both children very seriously in Dexter in the Dark. For example, while on a stakeout, he begins to wonder if Cody has brushed his teeth before going to bed and if Astor had set out her Easter dress for photo-day at her school. These thoughts distract him while he is waiting for an intended victim, which thoroughly annoys him. In the TV series, Dexter also takes a detour in his code of only killing murderers in order to dispose of a pedophile who is stalking Astor.
Animals do not like Dexter, which can cause noise problems when Dexter stalks a victim with pets. He is quoted as having once had a dog that barked and growled at Dexter until he was forced to get rid of it, and a turtle, which hid in its shell until it died of starvation rather than have to deal with Dexter.