Dexter: Original Sin will take audiences back in time to find out how the man became the monster — er, the monster-slayer — in the Showtime thriller.

The prequel series, which premieres on Paramount+ with Showtime on Friday, December 13, takes place 15 years before we first met Dexter (then played by Michael C. Hall, who still narrates the new series) in the original Dexter. Taking over the title role in this iteration is Patrick Gibson, who has the character’s steely-eyed stares and smug sauntering style down to a science.

With new characters being introduced in some familiar settings, the new series will bring some new details about Dexter’s past to light, but it will also inevitably retread some familiar territory from the first show, which had ample flashbacks.

Here’s what to remember about Dexter‘s past before Dexter: Original Sin. 

Dexter had a secret biological brother

Dexter didn’t find out until he was a fully grown serial murderer that he had a big brother who was also running around slaughtering people. The Ice Truck Killer who stalked Dexter was actually Brian Moser, his slightly older brother who was not adopted (or even mentioned) by Harry. Dexter only found out about Brian because the Ice Truck Killer left clues that were tailored to catch his attention — reminding him of scenes from his past as part of the Morgan family. 

His mother died in an unthinkable way

Laura Moser was the single mother to Brian and Dexter and worked as a confidential informant for Harry and the Miami-Metro Police Department against the Colombian cartel. She was brutally dismembered right in front of Brian and Dexter, who were left wading in her blood inside a shipping container. Harry adopted Dexter as his own upon finding him in the container, but Brian was sent into the foster system.

Dexter exhibited signs of a murderous tendency early on

In flashbacks in Dexter, it became clear that he was not a normal teenager with typical feelings or tendencies. In fact, he had an innate bloodlust that his father recognized and tried to quell with hunting trips, to the exclusion of his daughter Debra. Harry wanted to protect Dexter from himself — particularly his self-destructive impulses. 

His first kill was to protect his adoptive father

Though Harry tried to find other ways for Dexter to quench his thirst for blood, so to speak, he soon gave in and encouraged him to kill someone when he discovered Nurse Mary was poisoning Harry and other patients in the hospital after his heart attack. 

Harry taught him the code, which he continued to live by as an adult

Once Dexter began to kill, Harry worked hard to create a framework for his adoptive son to work within that, if he followed it to the letter, would keep his morality and freedom intact. The rules included being certain that the mark was worthy of being murdered and leaving no trace of evidence behind. Even after Harry’s death, Dexter worked to strictly adhere to this code in every kill. 

He had to fake being happy to fit in

Dexter repeatedly revealed that he felt empty on the inside, and it was Harry who taught him to feign normal human feelings and social interactions around others — even if it meant faking a smile in his own family photos.

His father had secrets, too

Little by little throughout Dexter, we learn that Harry Morgan had several affairs while married to Doris, including with Laura Morgan and another confidential informant. 

His adoptive mother also died when he was young

Though Harry is definitely the most common star of Dexter’s flashback memories, his adoptive mother Doris is also a fixture of his past. She died when Deb was 16 and didn’t know about Dexter’s violent tendencies, even if she didn’t totally understand him at times.

Dexter: Original Sin, Series Premiere, Streaming, Friday, December 13, Paramount+ with Showtime, Sunday, December 15, 10/9c, Paramount+ with Showtime

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