Brian Moser: Dexter Morgan's Brother
Brian Moser is the biological older brother of Dexter Morgan and the main antagonist of the first season of Dexter.
As a child, Brian witnessed the same traumatic event that led to Dexter's psychological development, but unlike Dexter, he was separated from his brother and spent years in psychiatric institutions.
As an adult, Brian became a serial killer known as the Ice Truck Killer, responsible for a series of murders throughout Miami. He eventually discovered Dexter's identity and attempted to reconnect with him, believing they were alike because of their shared past and homicidal tendencies.
Brian sought to convince Dexter to embrace his darker nature and abandon the moral code he lived by. His actions ultimately led to a confrontation with Dexter, making him one of the most significant figures in Dexter's life and one of the series' most influential antagonists.
Gallery
Method of Killing
He typically killed his victims by causing them to bleed out after restraining them. After they died, he would carefully dismember the bodies and remove all blood, resulting in the clean, bloodless crime scenes that became his signature.
He was known for being extremely meticulous. Rather than hiding his crimes completely, he often arranged body parts on crime scenes in deliberate ways, leaving clues and messages, especially for Dexter Morgan.
Enemies/Opponents
Dexter Morgan: His attempt to reunite with his biological brother failed as Dexter finds out that he kills innocent people, ultimately leading to him getting his throat slit by Dexter.
Law Enforcement: He faked his identity by using the name Rudy Cooper, however, people such as Angel Batista and Maria LaGuerta eventually found out, though Dexter was the only one who managed to catch him.
Psychiatric authorities and institutional staff: Attempted to limit his capacities during his youth.
Family
Dexter Morgan/Moser: His brother who he tried reuniting with. Both watched their mother get brutally murdered by a drug dealer with a chainsaw. Killed Brian Moser to protect his stepsister.
Laura Moser: His mother who he watched get murdered at 6 years old. There is not much information given about her in the original series.
Joe/Joseph Driscoll: His father. His relationship with Laura Moser and Brian Moser is not made clear in the series. Joseph Driscoll may or may not be his real name as Dexter found no records of his existence before age 30.
Spouse or/and Romantic Relationships:
Debra Morgan: Dexter Morgan's stepsister. Brian Moser manipulated her and proposed to her. He then choked her and tried to convince Dexter Morgan to be his true self by killing her. But Dexter Morgan saved her.