Teddy was raised by his single mother who really was a Skrull posing as a human who he believed to be his mother. Teddy did not know the true source of his power and assumed he was a mutant.
He had hidden his powers afraid of the backlash that comes with being a mutant, that is until he met Greg Norris who was the class president and captain of the basketball team. Teddy soon confided in him about his power and to his shock Norris was not upset. Greg, used his friend's powers to pull cons and pranks using Teddy's powers to shape shift into popular figures. After hearing of the break-up of the Avengers, Teddy was shocked. Greg used him to go into the wreckage of the Avengers Mansion. Teddy was in awe of the place and respected it, while Greg just wanted to use Teddy to loot the place. Teddy threatened Greg using his powers and he left the mansion.
Hulkling was created by Allan Heinberg and Jim Cheung.
Major Story Arcs
After Greg left, Teddy then met Kang who was gathering teens by using the Vision's fail-safe programing, to form a group of Young Avengers to fight Kang. Teddy agreed to join him and become Hulkling alongside Iron Lad (Kang), Stature (Cassie Lang), Patriot (Eli Bradley), Hawkeye and Wiccan (Billy Kaplan) with whom he kindled a close relationship.
After the Patriot quit the team the rest tried to talk him into coming back. While this happened, Hulkling was abducted by the Super-Skrull who said that Teddy was a Skrull himself and he had come to take him back. After a battle the group (minus Eli) escaped to Wiccan's house where they found who they thought was Hulkling's mother, but before anything could be made clear the Super-Skrull broke in with the Patriot as a hostage ordering Hulkling to come with him. The Super-Skrull then used a device that was supposedly supposed to reveal that Teddy was a Skrull but instead revealed that his mother was a Skrull. She stated that she was ordered by the Empress to protect Teddy and shot at the Super-Skrull who retaliated by setting her on fire, resulting in her death.
The Super-Skrull then took Hulkling and told him was Dorrek VIII and the son of Anelle, the Skrull Emperor's daughter, and the only heir to the Skrull empire. But the Emperor had ordered the child's death upon learning who his father was so Teddy was sent to Earth to be reunited with his father. Before the Super-Skrull could tell Hulkling who his father was, the other Young Avengers arrived to save Hulkling. Kree soldiers suddenly appeared claiming that Hulkling was Kree. The Kree soldiers then said that Hulkling was the son of Captain Mar-Vell and by law had to join the Kree army, but Hulkling refused and a battle broke out.
The Young Avengers fled, but then found themselves in the middle of another battle as Skrull and Kree Troops both appeared demanding that Hulkling come with them, but the the Avengers came to the rescue. The conflict was resolved when the Hulkling and the Super-Skrull switched identities and "Hulkling" agreed to a deal in which he would spend 6 months with the Kree and 6 months with the Skrulls before making a decision on who he would side with. The arrangement was still in order when the races left and Teddy returned to his original form, safe from both races and staying in Earth. After all was done Teddy scattered the ashes of his foster mother to the breeze at the Avenger's Mansion.
During Civil War, Hulkling, along with the rest of the Young Avengers, worked with Captain America for the anti-registration side.
Teddy joins the other Young Avengers, confronting the first wave of invading Skrull religious fanatics that arrive in New York City. Teddy attempts to reason with the Skrulls by revealing his identity as Dorrek VIII, but is incapacitated before his identity is revealed. Leaders of the invasion recognize him and allude to his ability to jeopardize their plans if their followers learn of his identity. Nearby, the Runaways also confront Skrull invaders. Recognizing the danger they pose, Xavin attacks and incapacitates the Runways, pretending to be one of the invaders and protecting them from capture. Xavin sends the Runaways to safety with Nico and Victor, but notices Teddy being attacked. He escapes with Teddy, attempting to save him, but both are attacked by other Skrulls.
Hulkling travels with Wiccan and the rest of the Young Avengers to locate the Scarlet Witch. After the deaths of Stature and Vision, he and his teammates agree to retire from being Superheroes.
Hulkling is confronted by Wiccan for sneaking out at night disguised as other superheroes in order to fight crime. The two fight, and Hulkling is able to get Wiccan to see his point of view. To make it up to him, Wiccan finds an alternate universe's version of Hulkling's adoptive mother, and she is reunited with her son. However, that night, she attacks Wiccan's parents. When Wiccan and Hulkling awake the next morning, they quickly discover that something is wrong. His "mother" tells them that they need to leave, and produces a sort of prison for them to stay in. The two go to the Uncanny Avengers for help, but for some reason they are unable to see anything wrong.
They are saved by Loki, who reveals that the being is an alternate dimensional parasite, and tells them that they need his help. Wiccan and Hulkling agree, but decide to first take Loki to New Asgardia, where they are attacked by Laufey. After fleeing from Asgard, the group continue to New York City, meeting up with Ms. America, Kate Bishop, and Noh Var. During the incident, Loki privately tells Teddy that he thinks that his and Billy's relationship is due to the latter's reality warping powers, and the thought disturbs Teddy. With Loki's help, the team are able to defeat the parasite, but because Wiccan's spell is still around, the team is forced to leave New York.
After three months in exile, Wiccan and the team are approached by the former X-Man and mutant Prodigy, who tells them that Speed, Wiccan's twin brother, was kidnapped by a mysterious figure wearing a Patriot uniform. The team agrees to look for Speed and they use Miss America's interdimensional powers to find him. When accidentally being left behind in Mother's dimension with Prodigy, Prodigy kisses him as a last act. The rest of the team, having briefly encountered Leah, returns to save them. Teddy, concerned that his relationship with Billy is fake, tells him that he needs some time alone. He later meets with his therapist - Leah.
Teddy joined forces with fellow teammates Noh-Varr and Prodigy to assess a threat after the "explosion" of force from one of Uatu the Watcher's eyes in Manhattan, NYC. The explosion implanted memories of events the Watcher witnessed into the minds of those nearest. These memories were specific to the person they affected. Teddy, Noh, and David were unaffected by the explosion, but did decide to help alleviate the damage caused by the situation. SHIELD immediately began the evacuation of all those who were affected by the explosion. Their fear was that those who had been exposed would now know too much for their own good. The trio came upon a building that had been ignored by the SHIELD agents, which was especially peculiar. Upon entering the building, they were confronted by the Red Hood, who had been using his mystical powers to conceal the building from SHIELD's scanners. After a brief struggle, Noh was able to use his enhanced speed to disarm the Hood, while Teddy managed to subdue him. The Hood explained that the residents of the building were going mad with the memories that had been implanted in their minds. He was trying to find a way to remove their memories so that he might help them. The trio was suspicious, but they agreed to help him. David used his powers to create a makeshift Cerebro that would allow him to remove their memories, and safely download them onto an encrypted file. While David worked, it would be up to Teddy and Noh to keep an eye on Red Hood. During this time, Noh and Teddy were contacting the other members of their team via text message. Billy, Teddy's boyfriend, wanted to help, but Teddy encouraged him to stay home and finish studying, while he took care of things with Noh and David. Eventually, David's contraption worked, allowing him to remove and download the implanted memories. Once the process was complete, Red Hood attempted to steal the device onto which the memories were stored. He was defeated yet again, and David later revealed that the encryption would only open to him. Unbeknownst to his companions, David kept a copy of all the secrets stored away just for him.
Avengers & X-Men: AXIS
Both Teddy and Billy made an appearance in Marvel's AXIS event. They appeared at Avengers Tower during a massive Avengers meeting called together by an inverted Sam Wilson aka Falcon aka Captain America. A new band of inverted heroes (Sam, Medusa, Scarlet Witch, Thor, Wasp) now with malicious intent, was furious that someone in possession of an Avengers ID card had allowed - and even helped - the recently captured Red Skull to escape the Tower. Billy and Teddy, along with anyone who'd ever held Avengers membership, were called to the Tower for this reason - to be dealt with by the new Avengers.
Teddy's super-human abilities stem from his parentage: a Skrull mother and a super-powered Kree father. As part-Skrull, Hulking is able to change his appearance by altering his size, shape, and color. When he increases his mass his strength also increases. He typically manifests claws and wings as necessary in battle. His Skrull physiology also gives him the ability to heal from injury at an accelerated rate and sub-consciously move and reshape his vital organs to protect himself from mortal damage. Teddy's shape-shifting abilities are detailed enough to bypass highly sensitive eye-scans and voice-scans.
As part-Kree, Hulkling inherited superpowers from his father Captain Marvel. This grants him super-human strength (far greater than the average Skrull or Kree) and enhanced durability.
Wiccan and Hulkling from the reality known as Earth A, came to Earth-616 as tourists and registered in the Initiative. The Wiccan and Hulkling of Earth-616 didn't approve of this, and later Wiccan and Hulkling from Earth-721 were sent home when the portal between worlds was closed.