Mark Blackthorn

Mark Blackthorn is a Shadowhunter residing at the Los Angeles Institute and is one of the many Blackthorn children. He was a former Hunter who rode with the Wild Hunt. He and his older sister, Helen, have the same faerie mother and are part-faerie.

History
Born to a Seelie Court faerie Lady Nerissa and Andrew Blackthorn in 1991, Mark and his older sister, Helen, were raised at the Los Angeles Institute with their father, and, like ordinary Shadowhunter children, were Marked when they were ten years old, during which Mark experienced some pain—a bit more than most Shadowhunters. Mark has five younger half-siblings: Julian, Livia, Tiberius, Drusilla and Octavian.

Despite being their half-brother, Mark had a generally good relationship with his younger siblings. Mark was even one of the few people who managed to get through to Ty during his bad moods.

As children, the siblings, including family friend Emma Carstairs, spent many rainy days making pillow forts. At ten years old, Mark was considered the proverbial "pillow fort expert", and the others would build the forts under his supervision.

Wild Hunt
Mark was around sixteen in 2007 when Sebastian Morgenstern and his army of Dark Shadowhunters attacked the Institute. Mark was on secondary supervision and was at the training room with the children and their tutor, Katerina. When the commotion began, Mark and Katerina left to investigate the situation. There, they joined the ongoing fight between the Conclave members and the Endarkened. After Katerina and Mark's father, Andrew, were Turned into Endarkened from being forced to drink from the Infernal Cup; Mark, who was originally meant to be Turned into Endarkened as well, was ultimately taken to the Fair Folk when Jonathan realized Mark was half-fey.

When the faeries were deciding on Mark's fate, Gwyn ap Nudd claimed him, and, after some time suffering through Meliorn whipping and torturing him, Mark was led to believe that his family was dead, so he ate and drank the faerie food he was offered so Meliorn would stop hurting him. Mark accepted that he no longer had a family to return to and officially became a Hunter of the Wild Hunt; causing one of his eyes to turn gold. Being in the Faerie, time flowed differently, and, though Mark had not been missing from his home longer than a week, he felt as though he had been with the Hunt for a seemingly long time. Regardless, thoughts of his family never left him.

During one of his visits to the Seelie Court with Gwyn and the other Hunters, he overheard some fellow hunters talking about how Gwyn had witnessed Clary Fray, Jace Herondale, Alec and Isabelle Lightwood, and Simon Lewis arriving to talk to the Seelie Queen. He then snuck away from the Hunters to the tunnel that led to Edom so he could find the group of Shadowhunters and finally inquire about his family. While Clary and Jace informed him that his siblings were actually alive, Mark was devastated, knowing that he can no longer leave the Hunt, which he wanted to do, to be with them—at least not without the permission he was unlikely to get. Nonetheless, Mark asked to go with them so he could reunite with his family, but Jace stopped him and reminded Mark that he had already sworn fealty to the Hunt and may face death if he tried to leave. Instead, Jace convinced Mark to simply warn the Shadowhunters of the faeries' conspiracy. Initially scared, Mark agreed. Before he left, Jace gave him his witchlight to help him metaphorically continue to see the light, even in the darkness.

Soon enough, Mark sent a message to the home of the Consul, which was coincidentally where his siblings were staying. He put the message in an acorn, in typical faerie fashion, stuck it to a fire poker, and shot it through their window. A pleased Ty found the message and gave it to Jules and Emma, who passed it onto the Consul, Jia Penhallow. Jules was able to confirm that the message was from Mark because he signed it with a blood stamp of their family ring. Jules and Emma insisted that the Consul try and get Mark back for them.

After the Dark War, because of their faerie blood, some Clave members, particularly Lazlo Balogh and Mrs. Sedgewick, questioned Mark and Helen's loyalties to the Nephilim and proposed that they discuss their fate. The majority of the Clave members, most of whom were furious and unforgiving about the fey's betrayal, voted to abandon the efforts to secure Mark's return, despite his family's objections. Similarly, his half-fey sister, Helen, was exiled to Wrangel Island under the guise of being sent to study the wards.

Though Mark made no friends among the Hunt, he eventually befriended the new recruit: Kieran, a former prince of the Unseelie Court. They began riding together, and they eventually fell in love.

For years after he was taken from them, Mark's room at the Institute was left untouched. Finally, on his eighteenth birthday on 2009, Julian cleaned out the room, putting all of Mark's belongings in boxes in storage. Though the room was vacant, it remained empty and untouched for years after.

Around this time in the human world—and much longer for Mark in fey time—Ascendant Simon was taken to the Faerie. When he found out that Simon was to be Nephilim, he helped Simon escape imprisonment from Hefeydd, asking him about his family before he left. Mark did not care that he was caught helping Simon and a Shadowhunter escape.

Returning home
In August 2012, Mark was returned to the Blackthorns as a bargaining chip. Iarlath and Kieran came to the Los Angeles Institute and offered to return Mark to the Blackthorns if they helped investigate the recent murders of the faeries—a transaction that broke the Cold Peace.

Physical description
Mark is tall, thin, has broad shoulders, and bore the signature blue-green eyes of the Blackthorns. However, since Mark became part of the Wild Hunt; his right eye has since turned gold. Like Helen, he also has pointed ears and pale white-gold hair that curls in ringlets. As they both share their mother's faerie blood, both have a rather delicate bone structure.

While Mark was gone for five mortal years, time moved differently in Faerie and so Mark aged differently. Mark appears only around three years younger than he really is, looking around the same age as Julian.

Personality
Mark is quite serious and somber, having been alive for much longer than his age would suggest, and having been through a lot of trauma for someone his age. Also, because of the time he has spent away from humans and among faeries, Mark no longer easily catches onto sarcasm or humor.

When he was younger, Mark was impatient and easily annoyed; like a typical teenager, he believed himself more mature and above his younger siblings. Nonetheless, he loved and cared for them deeply.

Mark also enjoys reading.

Skills and abilities
Due to the angel blood in their veins, all Shadowhunters are able to apply runes on their skin without any real danger. These Marks, in turn, give varied effects that serve to benefit the wearer.
 * Nephilim physiology: Being Nephilim, Mark possesses a variety of enhanced physical and mental abilities granted to him by the blood of Raziel in his veins and also by the angelic Marks of the Gray Book. He also has power to perform tasks unique to their species, such as the ability to use and call on the power of the angels for their seraph blades. This includes enhanced strength, agility, stamina, and coordination, which only improves over time and practice.
 * Runic magic:
 * Accelerated healing: Mark and all Hunters are protected by magic that significantly hastens their healing process, though this does not enable them to recover as fast as a Shadowhunter's iratze would, and wounds do not fully heal and may leave more scars than when an iratze is used.
 * Sensing: Due to his years of training among faeries, Mark is able to sense certain elements, such as ley lines and convergences.
 * Marksmanship: Mark is a master at archery and is a spectacular marksman, owed to his years of experience as a Hunter.

Weapons
Hunt; its magical substance and nature allowed it to change its form from a horse to anything that would fit any world—such as a motorcycle, that could still fly, in the mundane world. It was destroyed by a Mantid demon.
 * Blades: As a young Shadowhunter, Mark used to favor curved, single-edged blades, like katanas, as his primary weapons.
 * Faerie steed: Mark's brown Faerie steed while with the
 * Bows and arrows: As a member of the Wild Hunt, Mark primarily used bows and arrows.
 * Elf-bolt: Given one by Kieran, Mark was skilled and able to master the use of the deadly, poisonous faerie weapon. It became his favorite weapon. Mark used to wear its tip on a chain around his neck, though he eventually returned it to Kieran.

Trivia

 * As a half-fairy, he can tell lies. Pure fairies can not do that.
 * He can feel when other downworlders are nearby. He even knows exactly what "breed" of fairies or other downworlders it is, and whether they are half-human hybrids or pure downworlders.