The son of the Magistrate is a member of the Gibborim race. Once released from the spaceship he was trapped in, he possessed Alex Wilder. Due to Wilder's stubborn personality, he remained dormant far longer than the other members of his family, but eventually managed to control Wilder's body after he was shocked by the news of his mother's death. He made a deal with his father: in exchange for delivering Elle Dean, the second child the Magistrate had conceived with Leslie Dean, he would be allowed to remain on Earth with the Gibborim Scrub Squad. However, his plans were foiled by the Runaways when Nico Minoru cast a powerful spell which forced the Magistrate's son to give up on Wilder's body.
The Magistrate's Son was exiled from his home planet with the rest of his family as punishment for something that, according to his father, he was responsible for. The family departed their planet on a spaceship steered by Xavin, a Xartan stowaway the Magistrate had discovered on board. The spaceship crashed on Earth in modern-day Los Angeles, with only the Magistrate being able to escape. The Magistrate's son remained trapped in the wreckage with the others for 11,000 years.
Taking Leslie Dean
As Wilder, the Magistrate's Son destroyed Victor Stein's x-ray glasses which could be used to identify him. He and Wilder fought as the latter visited his mother Catherine in prison, who later died. Wilder got a call about his mother's death from his father Geoffrey, but the Magistrate's son took over for good, smiling and saying that it was time to leave.
He went to Leslie Dean's bedroom in the Hostel and read her unborn baby's biomarkers, discovering that the Magistrate was the child's father. He told Dean that something bad had happened, claiming that the Magistrate found them. He told her that he would keep her safe.
At Randy's Donuts the Magistrate's son called his father, saying that he didn't want to leave Earth, against his father wishes, offering him Dean's son in return. The Magistrate agrees to the deal, and gets donuts from the store, killing the man who sold them to him with his Gibborim powers. However, Dean's water broke. Since the family had to leave before the hospital would release Dean and her child, the Magistrate's son drove Dean to Tamar's house, thinking that having a child means she knows how to deliver one. Tamar helped them anyway, and Dean claimed to need lavender oil in order to give birth, so Tamar had the Magistrate's son, who she believed to be Alex Wilder, get it from Dean's car. While he was gone, Dean told Tamar that something was off with Alex, and told her to get her son safe and run away.
When the Magistrate's son returned with the bag, Tamar had him take Dean into her bedroom, instructing him to hold her hand and not let go. She claimed to be searching the Internet for instructions on how to deliver a baby, but really retrieved her phone and contacted Karolina Dean, telling her where to find her mother. The Magistrate's son figured out that Tamar had left, and turned against Leslie. He threatened her and her child, but Tamar returned and knocked him out with a baseball bat. It didn't last long, however, and the Magistrate's son tied her to a chair.
He started to choke her using his powers, but the Runaways showed up, prompting him to run. Tamar gave Karolina and Nico Minoru a gun in order to stop the Magistrate's son, resulting in a chase between the three of them. He was trapped behind a fence, and found Minoru pointing a gun at him. However, he was confident that she wouldn't shoot him, because of the friendship between Minoru and Wilder. He threatened to jump into Minoru's body and shoot Karolina, so Minoru let him run away.
As his family prepared to leave from the Marine Vivarium Desalination Plant, the Magistrate's son kidnapped Leslie's child, named Elle, and his parents fought about whether he should be allowed to stay. The Magistrate convinces his wife when his son reveals that he plans to join the kill team that is planning to come to Earth and kill all people who have been in contact with the family and start a Gibborim colony on Earth. The Magistrate's son helped his family open the portal to Gibborim, but the Runaways arrived before they could all leave.
The family fled as the Runaways prepared to fight them. While Chase Stein fought the Magistrate, Gert Yorkes and Molly Hernandez fought his wife, and Nico fought his daughter, the son fled with Elle. Xavin approached him disguised as the Magistrate and retrieved Elle, instructing the Magistrate's son to help the rest of his family in the fight. As Xavin took Elle to Gibborim, the Magistrate and his family returned. The four members began to overwhelm Karolina with their powers, causing pain to all of the Runaways. However, they were defeated by Nico Minoru, causing the Magistrate's son to be forced out of Wilder's body.
- "On the surface, he projects no shortage of what you would call charm. He's amiable. Able to put people at ease. But under the surface there's a cruelty that has become legendary to my people. He's notorious for the pleasure he takes inflicting pain on others. Especially the innocent. Very few have escaped his wrath. Those who did were never the same again."
The Magistrate's son has a very violent personality, killing people for fun. He murders a worker at Randy's Donuts merely because he enjoys it, and tells Tamar that he wished her son could have witnessed the fun of him killing her. He planned on joining the Gibborim crew that would kill all humans who had contact with the Magistrate and his family.
He is also very deceptive. It took Leslie Dean a long time to figure out that he had won the battle for control of Alex Wilder's body, despite killing the donut salesman in plain sight. He also manipulated Nico Minoru into not killing him, further demonstrating his deceptive nature.
As he tells Minoru, he enjoys being on both the receiving and delivering ends of pain. This can be both physical or emotional, as he enjoys killing and encouraged Minoru to shoot him, but also enjoys the concept of emotional pain caused by things such as making Minoru shoot Karolina Dean and watching her girlfriend's shocked reaction.
- Gibborim Physiology: The Magistrate's Son is part of an extraterrestrial species known as the Gibborim. He possesses various superhuman attributes that are common among his kind.
- Longevity: The Magistrate's Son, with the rest of his family and Xavin, was able to survive in a state of suspended animation for over 11,000 years after crash-landing on Earth.
- Possession: Like the rest of his species, he must possess a human in order to survive Earth's atmosphere. Upon being released from the wrecked ship beneath the PRIDE Construction Site, he possessed Alex Wilder and gradually took control of him until he had achieved full possession of his body, leaving Wilder's personality dormant.
- Light Weapons: The Magistrate's Son is able to manipulate light as a weapon. He has demonstrated the ability to shoot bolts of light from his hands, and to create a rope of light to throttle his targets.
- Light Beam Emission: He is able to project beams of light to attack and incapacitate enemies.
- Volvo XC90: During his possession of Alex Wilder, the Magistrate's son used this car in an attempt to take Leslie Dean out of the Hostel so he could bring her to-be-born baby to his father.
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