“Dexter: Original Sin” serves as a prequel, showing how Dexter Morgan became the serial killer we know. At first, it seemed like the story would have few surprises. We already knew Dexter and his sister, Debra, would survive.
Even when the show introduced Dexter’s brother, Brian, we understood that the two would not meet until later in the timeline. This meant that the story could only unfold in a few possible ways.
However, “Dexter: Original Sin” proved that it could still create plenty of suspense. The season kept viewers on edge with multiple questions. Would Aaron Spencer, the main villain, be caught before harming his young son, Nicky? Would Bobby survive after being shot? Would Brian get closer to Dexter?
The biggest question remained—would Harry Morgan survive? Since we know from the original series that he is dead, the uncertainty about how and when it would happen made the season even more intense.
Also Read: Dexter Ending Explained: What Happens to Dexter Morgan in the Finale?
Dexter and Aaron Spencer Face Off in a Final Battle
In the second-to-last episode, Dexter captures Aaron Spencer and restrains him on his table. Just as he is about to kill him, Spencer reminds Dexter that if he dies, no one will know where his son is, leaving the boy to starve. Dexter realizes that Aaron will not reveal Nicky’s location easily.
Instead of killing him, he lets Aaron go but follows him. Dexter knows that Aaron, desperate to see his son, will lead him right to Nicky.
Aaron has been keeping Nicky captive on an abandoned ship. He approaches his son, who is chained to the floor, but before he can harm him, Dexter makes noise to distract him. This forces Aaron to step away from Nicky. Dexter finds the boy trapped inside a pit.
However, Aaron has a backup plan. He starts filling the pit with water, making the situation worse. The rising water threatens to drown Nicky. Even Dexter, who has seen many terrible things, is shocked by Aaron’s cruelty.
Aaron gives Dexter a choice. He can kill him now but let Nicky drown, or he can save Nicky and allow Aaron to escape. Dexter may be a killer, but he has his own principles.
He decides to save the child. As Aaron runs away, Dexter jumps into the pit. Nicky is already unconscious by the time Dexter reaches him. He gives the boy mouth-to-mouth resuscitation, bringing him back to life.
Now that Nicky is safe, Dexter turns his attention back to Aaron. He knows exactly where the man will go. Aaron’s rage comes from the truth about Nicky. He is not the boy’s biological father. His wife left him for another man and started a new, happy life. Meanwhile, Aaron is consumed by anger and pain. He decides to take revenge on her.
Aaron arrives at his ex-wife’s home and attacks her husband first. Then, he tries to reach her. She runs to a bedroom and locks herself inside. Just as Aaron is about to break in, Dexter arrives. He injects Aaron with his signature tranquilizer, knocking him unconscious.
When Aaron wakes up, he is tied up on Camilla’s boat. Dexter kills him and disposes of the body in the harbor. This moment is important because it is the first time we see Dexter using this method of getting rid of a body. He thanks Camilla for the idea.
Later, when he talks about the experience with his father, he realizes something. Some people deserve to die, while others deserve to live. This shows that Dexter is not just following a set of rules but is also guided by his own sense of right and wrong.
Brian Moser’s Heartbreaking Journey
The most emotional part of the finale belongs to Brian Moser. In the original series, Brian is presented as cold and evil. However, in “Dexter: Original Sin,” we get to understand him better.
As children, Brian and Dexter saw their mother killed inside a shipping container. After the traumatic event, Brian was the one who comforted his younger brother. However, after they were rescued, they were separated. Harry took Dexter in, while Brian was left behind. He never received love or support. His life became a series of painful experiences.
Brian was placed in a foster home, but things did not go well. A boy locked him in a closet, and Brian had to fight back on his own. In another home, when a child stole his food, Brian responded violently, stabbing him in the hand with a fork. He had no one to protect him, so he relied on his rage.
Eventually, Brian was sent to a mental institution. There, he found one person who treated him kindly—an orderly. However, when that person started taking away his medication, Brian lost control and attacked him. He was constantly mistreated and ignored, even though all he wanted was to see his brother again.
Brian had a therapist, but his therapy sessions did not help. The therapist warned him that seeing Dexter was a bad idea. He even threatened to send Brian back to the hospital if he continued asking about his brother. That was Brian’s breaking point. He only wanted to heal so he could reunite with Dexter. If he could not do that, he saw no reason to keep trying.
Brian snapped. He killed his therapist and then went after everyone who had wronged him in the past. This included the social worker who had separated him from Dexter. He left her body on a rooftop, hoping Dexter would find it. However, Dexter was busy dealing with Aaron Spencer. Instead, Harry and other police officers arrived at the scene.
From another rooftop, Brian watched them. Harry saw him and decided to confront him. Their conversation was filled with tension. The audience had always been told that Harry died of a heart attack. Now, they had to wonder—was this how he would actually die?
Brian pointed a gun at Harry and expressed his anger. He talked about being abandoned, being mistreated, and never being given a chance. He even blamed Harry for their mother’s death. What made this moment tragic was that Brian was not entirely wrong.
Harry admitted to making mistakes. However, he insisted that Dexter was better off with him. He believed he had given Dexter a better life. Brian, overwhelmed with emotions, pulled the gun toward himself. He wanted Harry to shoot him.
When Harry hesitated, Brian knocked him unconscious. But instead of killing him, Brian left a message written in Harry’s blood. It told him that he had been right all along.
Harry Morgan’s Fate and Debra’s Big Decision
The season ended on a hopeful note. Aaron Spencer was dead. Brian decided not to kill Harry. Bobby survived, bringing comfort to Debra.
While Bobby was unconscious, Debra spoke to him about her struggles. She cried, but it also helped her process her emotions. At school, she apologized to her best friend. More importantly, she made a big decision about her future.
At a family dinner celebrating Dexter’s new full-time job at the police department, Debra made an announcement. She decided not to pursue a volleyball scholarship at Florida State. Instead, she wanted to become a police officer, just like her father.
She signed up for the academy. Harry and Dexter supported her decision. She even joked that they would have to start including her in their secret conversations. This led to a brief but meaningful exchange of glances between Harry and Dexter.
The family ended the night by dancing together. For a moment, everything seemed happy. However, tension still lingered. Would Harry collapse right there on the dance floor? Thankfully, he did not.
Outside, Brian watched them from a distance. He saw the happy family he could never be part of. The season ended with this powerful image.
A Powerful Ending That Leaves a Lasting Impact
“Dexter: Original Sin” successfully delivers a thrilling and emotional prequel that keeps viewers engaged until the very end. The season finale ties up major storylines while leaving enough room for future developments. Dexter’s battle with Aaron Spencer highlights his commitment to his own moral code.
By choosing to save Nicky instead of killing Aaron immediately, Dexter shows that he is not just a killer—he has his own sense of justice. His first experience with disposing of a body in the harbor marks a defining moment in his evolution.
Brian Moser’s tragic past adds depth to his character, making his transformation into a ruthless killer more understandable. His confrontation with Harry is both intense and heartbreaking.
Although he spares Harry’s life, his pain remains unresolved. Watching the Morgan family from the shadows reminds us that he is forever an outsider, unable to share in their happiness.
Debra’s decision to become a police officer is another crucial moment. Instead of chasing a different future, she chooses to follow in her father’s footsteps.
The season ends on a hopeful note, but the lingering tension suggests that darkness still lies ahead for the Morgan family. “Dexter: Original Sin” proves that even prequels can be filled with surprises, suspense, and emotional depth.
“Dexter: Original Sin” is available for streaming on Paramount+ with Showtime in the U.S.
Also Read: “Dexter: Original Sin” Brings New Twists to a Dark and Gripping Story
