How does Brian Moser turn into a serial killer in Dexter: Original Sin? Character arc, explored

Dexter: Original Sin, the prequel series to the hit show Dexter, is continuing to expand the lore of the beloved serial killer, Dexter Morgan.

The latest episodes of the spin-off have proved that it is not only expanding on Dexter's formative years as a killer but also on the people around him, like his brother Brian Moser, the infamous Ice Truck Killer from the original show.

Harry has been suspecting that Brian might be the NHI Killer, which has revealed the backstory of the sibling's mother's death and how it affected them.

Dexter: Original Sin's latest episode confirmed that Brian became a serial killer out of revenge and the trauma he saw during the Shipping Yard Massacre. After his violent outburst, Harry decided to separate the two brothers, after which Brian became a serial killer.

More on Brain's backstory in Dexter: Original Sin in our story.

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Dexter: Original Sin shows Brian Moser did not have a guardian like his brother

While nobody can justify Dexter's actions, it can be argued that Harry had a big influence on him, which kept him in partial check before his eventual death.

While Dexter had a guardian and fatherly figure even after his mother's death, his brother, Brian Moser, had none. As shown in Dexter: Original Sin Episode 9, Dexter and Brian were seven years old during the Shipping Yard Massacre from the original series, during which their mother, Laura, was brutally killed.

Both the siblings saw the brutal murder of their mother, after which they were taken in by Harry and his wife. While Dexter faced less difficulty with Harry because he knew him before, because of his affair with his mother, but Brian did not.

After his mother's death, Brian turned extremely violent, even suffocating Deb with a pillow, which forced Harry to separate the brothers and abandon Brian eventually, leading to the dark and sinister serial killer path he later took.

As shown in Dexter: Original Sin, Dexter, and Brian both turned into violent serial killers after their mother's deaths. However, since Brian had nobody to look after him, he did not have a code like his brother.

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Brian is headed on a vengeful path in Dexter: Original Sin

As clear from Barb's murder in Dexter: Original Sin, Brian is headed on a vengeful path in the prequel series. Barb is the social worker who promised to keep the two siblings together, and since Brian was separated from his brother, she became his target.

He killed her with a chainsaw, mimicking his mother's death. But Barb is just the first victim who has been checked off Brain's revenge list, and his bloodbath will continue for some more episodes.

His early outburst with Deb suggests that she might fall prey to Brian because she had a main role in the original Ice Truck Killer arc. But since Deb dies in Dexter Season 8, Brian will not be able to kill her in the prequel series just yet.

But the same cannot be said about Harry, who is most likely number one on Brian's killing list because he abandoned him and separated him from his brother. Since Harry has now started his investigation about Brian being the N.H.I. Killer in Dexter: Original Sin, the show might reveal that he had a hand in Harry's death.

Since the original series established that Harry died of suicide by overdosing on his heart medication, the prequel show might surprise fans and reveal Brain had a hand in Harry's suicide, which would be in tune with his character right now.

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