OOC.
Teddy Altman is a Marvel character, from the 616 (main comic book) universe. He has not, as of yet, appeared anywhere in the MCU.
Believing himself to be a mutant with shape-shifting abilities, super-strength and a healing factor, he joined the original Young Avengers team as the superhero Hulkling, along with Eli Bradley (Patriot), Nate Richards (Iron Lad) and Billy Kaplan (Asgardian). Later developments revealed that he is actually a Kree/Skrull alien hybrid, with abilities derived from both sides of his parentage.

He is either bisexual or gay in comics canon, and the only relationship we've seen him in / attraction he's expressed is his long-term partnership with Billy Kaplan.
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Theodore Dylan goes by his middle name, and always has. His mother is English by birth, and his parents met when his American father was studying in the UK for a year. She immigrated back to the USA with him, and while Dylan is naturally aware of his English side, he doesn't particularly identify with it. More family members came over to the States when Dylan was young, and he grew up mostly unnoticed within a vaguely chaotic but large and loving extended family.
He grew up in Brooklyn, was a skinny little pisher in high school, and only came into his height and muscle in his senior year. He's bisexual, but has never really been in a relationship. He was too invisible in high school, too freaked out his first year of college, and too busy now for anything serious. Really.
He shares a tiny and terrible apartment with his cousin Bessie Ford, and they get along well enough. It's nice to have someone in his corner.
Dylan has self-esteem issues that he's hidden by being the affable sports-jock, but he's taken the plunge and gone into art in college. His parents have encouraged him to follow his dreams, but he's still on the fence about what those dreams actually are. So for now he's sticking with the thing he knows he can be good at, rather than try something new and fail.
19 years old, in his second year at NYU Steinhardt (BFA)