Season One consists of the first twelve episodes of the Showtime series DEXTER. The season originally aired in 2006, marking the initial adaptation of Darkly Dreaming Dexter to a television audience.
Season One of DEXTER was the only season to be almost directly related to the novels, specifically Darkly Dreaming Dexter. Subsequent seasons featured original storylines.
The first season received high ratings for Showtime. The pilot episode "Dexter" attracted more than a million viewers, giving the channel its highest ratings in nearly two years, while the finale "Born Free" drew an audience of 1.1 million viewers in the U.S. On average, the season was watched by two million viewers per episode during its original run when factoring in DVR viewers.
The show's first season received generally favorable reviews from critics; it was praised as "bold, different and exciting, with a central character and performance that take your breath away" by the New York Daily News. The Wall Street Journal saw "the grotesqueries of Dexter" as "not something that can easily be dismissed with the old "'you don't 'have to watch' line" and concluded that, "We do have to live among the viewers who will be desensitized, or aroused, by this show." The aggregate site Metacritic scored the show's first season at 77 out of 100 based on 27 critics reviews.
Meanwhile, Dexter is romantically involved with Rita Bennett, a single mother whose abusive soon-to-be ex-husband, Paul Bennett, is released from prison on parole. While Bennett is good to their children, he repeatedly — but unsuccessfully — attempts to get back with Rita. After Bennett threatens him, Dexter knocks Paul out with a frying pan, and then sets him up to look like he violated his parole by using heroin. While back in prison, Bennett insists that Dexter set him up and to look for a missing shoe, but Rita ignores him.
Debra Morgan begins dating a prosthetics doctor named Rudy Cooper — who is secretly the Ice Truck Killer. After they get engaged, Cooper kidnaps Debra and lures Dexter to the house where he is keeping her. Cooper is revealed to be Brian Moser, Dexter's long-lost brother. Brian remembers that, as children, they witnessed their mother's brutal murder at the hands of drug dealers, who then left them in a shipping container for two days, sitting in a pool of blood. Dexter learns that Brian spent much of his childhood in an institution. Brian then brings Dexter to a bound Debra, intent that the two of them will kill her together to cement their bond and sever the ties between Dexter and his adoptive family. Dexter hesitates for a moment, unable to kill Debra, which angers Brian. Dexter engages in a struggle with Brian to stop him from killing Debra. Moments later, the police arrive and Brian escapes.
After luring Brian into a trap in his apartment, Dexter drugs him, and takes him to Brian's residence. He kills Brian there, making it look like a suicide. Everyone, including Debra, remains unaware of the family connection between Dexter and Brian. Dexter feels some regret over killing Brian, the one person who fully understood him, in order to save Debra, who he feels would reject him if she ever learned his true nature.
Dexter premiered on October 1st, 2006 with the episode of the self title Dexter. The season set up the usual 12 episode format of one hour running time. This is normal considering most half-hour shows run about 24 episodes a season.