- “Dear Teddy, you are without a doubt the best boyfriend in the entire world. You're kind. You're generous. You threaten to maim people for me.”
Billy and Teddy were both selected for the Avengers Fail-Safe Program (a program designed to assemble a new team of superheroes in case the Avengers were disbanded), and joined the Young Avengers with team members Iron Lad and Patriot as Asgardian and Hulkling. The two began dating not long after.
The couple seems to have grown close over a significantly short time, as Teddy states during the attack of Kang the Conqueror that Billy learned his spell-casting from reading Teddy's mother's self-help book.
After having prevented the destruction of the timeline, Billy having officially changed his code name to Wiccan, he decides now would be a good time to reveal his aspiring superhero identity to his parents. However, the Kaplans misread his intentions and assume he was coming out about his relationship with Teddy. Nonetheless, they are very supportive of the two, and even go so far as to call Teddy an "excellent son-in-law".
When Teddy is shot during the attack of a terrorist group, he is taken hostage and the gunman threatens to detonate a nuke strapped to his back. Sensing that his boyfriend is in grave danger, Billy's powers overload and send the entire group comatose.
Whilst attempting to stay on Billy's side, Teddy is afraid of what would happen if Billy lost control of his powers again. Agitated, Billy dismisses Teddy's attempts at a conversation and leaves, only to run into Captain America in his home. The man convinces Billy to come with him to the Avengers Tower to test his powers, but they are soon stopped by Teddy. Teddy warns Captain America that if anything happens to Billy, he should not be worried about Billy but rather what Teddy would do, and that where Billy goes, Teddy follows. Surprisingly to the couple, Captain America is not troubled by this and in fact invites Teddy to share a room with his boyfriend during the test.
The room turns out to be something more akin to a dungeon, but Billy uses his magic to transform the twin beds into a king-sized one. The pair begins to embrace, and Billy apologizes for the events that transpired, and Teddy assures him that what happened was out of his control and the Avengers' tests would be harmless. The couples tries to kiss, but is interrupted by an unhappy Tommy, who transports them out of the tower. The touching reuniting moment is stalled by the appearance of Magneto, the twin's grandfather.
When the Avengers attack Magneto, Teddy is seen protecting Billy from danger on numerous occasions, as when Wolverine tries to kill him. Teddy also humorously expresses that he's never been as attracted to Billy when he decides to not give a damn what the Avengers will do to him and brings the entire team and Magneto to Transia. Teddy objects to Billy's idea to send them home, and he is convinced by the team to let them help. To make their attire less suspicious-looking, Billy transforms their clothes into those of the movie "Sound of Music", Teddy explaining that it is Billy's favorite film, to which his boyfriend interjects saying that it is one of his favorites.
The Young Avengers disband after Iron Lad disappears into the time stream. Billy falls into a state of depression, which Teddy brings him out of by proposing to him. Before they can celebrate, though, they are summoned to the Avengers Mansion, where Captain America declared the remaining Young Avengers as full-fledged Avengers.
Billy and Teddy briefly retire from being superheroes. They return to heroics when Billy, attempting to manipulate reality to make up with Teddy after an argument, accidentally allows an interdimensional parasite called Mother masquerading as Teddy's mother into the world. The Young Avengers reunite to defeat Mother, chasing her through the Multiverse. After returning to Earth, Teddy leaves the team to figure out whether he truly loves Billy or if their relationship was a result of his reality-warping power.
Teddy accidentally lets Mother back into Earth. Still too weak to end the spell that initially brought Mother to Earth, Billy tries to tap into the power of the Demiurge, an omnipotent entity that he is destined to become. He is unable to, however, until he is reunited with Teddy. Teddy comforts him and reconciles with him, giving Billy the strength to reach his full potential, and he finally destroys Mother.
The two join the New Avengers, but later decide to disband the team and focus on their personal lives.
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