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Arthur Blackthorn

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Arthur Blackthorn
CJ Flowers, Arthur
Biographical Information
Born: 1973[1]
Status: Alive



Head of the Los Angeles Institute


Los Angeles Institute
London Institute (former)


The Clave


Andrew Blackthorn † (brother)
Eleanor Blackthorn † (sister-in-law) Helen Blackthorn (niece)
Mark Blackthorn (nephew)
Julian Blackthorn (nephew)
Livia Blackthorn (niece)
Tiberius Blackthorn (nephew)
Drusilla Blackthorn (niece)
Octavian Blackthorn (nephew)
Blackthorn family

Physical Description
Gender: Male
Hair color: Dark brown; graying
Eye color: Blue-green

Arthur Blackthorn is the current head of the Los Angeles Institute.



Both Arthur and his older brother Andrew were originally from London. They were raised by parents who were obsessed with Ancient Greek and Latin works, resulting in a shared fascination for it. Arthur himself eventually grew obsessed with the classics.[2]

Fair Folk

During his first year at the Academy, Andrew and Arthur were among ten students, accompanied by one of their teachers, sent to the Faerie to rescue a female Shadowhunter child that had been taken. While he normally would not have been part of the mission, he was allowed to accompany his brother, as everyone knew the pair always fought side by side.

When Andrew fell in love with Nerissa, a lady of the Seelie Court, Arthur insisted on staying with him. While Andrew and Nerissa became lovers, her sister laid claim to Arthur. He was then tortured throughout his stay, with his brother unaware of what was being done to him. When Andrew found out the truth. Nerissa, worried that Andrew would go mad with grief and guilt, made new memories for them. She also set up their "escape" by releasing Arthur, who then attacked her to rescue Andrew, and Nerissa let them believe that she had been killed.

After around seven years, the brothers returned to their world to find that only a day had passed since the day they chose to remain in Faerie. They reported everything they believed happened to the Inquisitor.[3]

Arthur eventually returned to the London Institute while Andrew went to Los Angeles. Though their relationship was no longer as it used to be due to their traumatizing experience with the faeries, the brothers stayed in contact and remained close. Arthur visited the family, particularly during the holidays, and he often sent the children Latin works as gifts.[4]

Meanwhile, Arthur conducted research at London's museums, befriending mundane curators to gain access to private collections.[1]

Dark War

After the attack on the Los Angeles Institute and the capture and subsequent Turning of Andrew into an Endarkened by Sebastian Morgenstern, Arthur was contacted by the Consul, Jia Penhallow and offered the leadership of the Institute as well as the guardianship of his brother's children. Arthur did not immediately agree to this offer, presumably due to the suddenness of the news. A few days later, the London Institute was also attacked by Sebastian and his Endarkened warriors, though the attack was deemed unsuccessful; even still, Arthur was injured in the battle and needed a cane for support afterward.

On the day of his arrival in Idris, Arthur attended the Clave meeting in order to discuss their post-Dark War plans. When some members suggested that the Clave strip his niece Helen of her Marks, Jia asked him to speak, and he publicly accepted the responsibility of taking care of his brother's children as well as the Institute. His nephew Julian was dismayed, as he had briefly hoped that he would no longer desire to help, and thus the Clave would be forced to make Helen their guardian. Though Arthur tried to vouch and plead for the loyalty and integrity of both Helen and her brother Mark, believing that they are both good Shadowhunters despite their faerie blood, a sentence was still passed down by the Consul: Helen was exiled to Wrangel Island indefinitely to study the wards, and the Clave also voted to abandon the search and rescue of Mark from the possession of the Wild Hunt.

Before the family left for Los Angeles, the issue of Emma Carstairs and her bond with Andrew's children was broached, and Arthur agreed to take Emma in as well, even before she became Julian's parabatai—a notion his nephew appreciated. Helen also tried to talk her siblings into trusting Arthur, with whom she, along with Julian, wanted to believe in and entrust her other siblings.[4]

When Arthur arrived, however, it became clear that he would not be of any help to the children. He was not particularly kind when he introduced himself to the children, especially to Ty, whom Arthur dismissed as weird and different, and he hardly interacted with them at all. Even worse, Julian soon discovered that Arthur had lost his mind, due to the losses he suffered during the war,[5] making him incapable of running the Institute and looking after the Blackthorns.

In order to keep his family together, Julian secretly ran the Institute in his stead. Arthur rarely left the attic, where he spent most of his time studying, lost in his own head. To keep up the pretense that Arthur was the head of the Institute, Julian had Malcolm Fade make medicine that made him lucid for a few moments. Meanwhile, Julian personally looked after him and his own siblings. Arthur would often mistake Julian for his father, Andrew, because of their resemblance and his own lunacy.[2]

Physical description

Arthur resembles his brother, albeit smaller and paler. He has a slight figure, a round face, brown hair, and the trademark Blackthorn blue-green eyes. He also wears spectacles.


Arthur was named after King Arthur.[6]



  • Arthur's favorite weapon is the dagger.[1]
  • Arthur has been known to say that Lady Nerissa, Helen and Mark's mother, is alive, even though she is known to be dead. This is possibly due to his mental illness, which causes him to see people who are not there.[2]


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