Oneleigh Stark

Oneleigh Maria Stark is the oldest daughter of Tony Stark born to a former fling Caroline Bergland. She is the stepdaughter of Pepper Potts and Sam Wilson and the older paternal half sister of Morgan Stark. She is (post-posthumously on their part) the granddaughter of Howard Stark and Maria Collins Carbonell Stark.

She joined the Avengers during the fight in Wakanda against Thanos' forces as a battle-capable field medic with her mother describing her as needing to be an 'Iron Cross', a play on the Red Cross and Oneleigh's father's hero name of Iron Man, and she adopted the name officially as her hero name during the battle.

She is a protege of her father and Natasha Romanoff, who took on an almost aunt-like role in her life. She is like a niece to Happy Hogan, Steve Rogers, Clint Barton, and Wanda Maximoff. She is like a niece and is the goddaughter of James Rhodes. She is also the girlfriend of Peter Parker, the Spider-Man.

Birth
Oneleigh Maria Stark was born January 25th, 2004 in her mother's hometown of Cedar Rapids, Iowa. She was named Oneleigh by her mother, and given her middle name by her father after her late paternal grandmother.

Stark states that Oneleigh weighed 6 pounds and 9 ounces at the time of her birth. He also states that when she was born he truly felt afraid that he wouldn't do right by her. He did sign the birth certificate and held his daughter but didn't stay long after doing so.

James Rhodes was named to be her godfather by her dad and took on a role as she grew older that was like an uncle.

2004-2009
Due to his fear of messing his child up mentally or emotionally, Stark was almost non-existent in his daughter's life. This means that during this time she was raised entirely by her mother, though her father did send gifts and money as needed though her mother rarely asked/accepted the latter.

Her father was kept updated on his daughter's life through updates given by her mother to his personal assistant, Pepper Potts, but he only saw her a couple of times in person. He outwardly claimed that he had no desire to do so but later admits that this was a lie and that he had wanted to see her all along but convinced himself that he didn't believing that she was better off without him.

He did however have her enrolled in programs to learn foreign languages during this time, hoping to prepare her to perhaps some day take over the company if she wanted.

After her father was located in Afghanistan, with many believing him dead, she greeted him at the airport running to embrace him as she exclaimed, "Daddy!". This contradicted a claim that Stark had made in Afghanistan to Ho Yinsen that his daughter probably didn't even know who he was.

She was present at the press conference where her father announced the end of weapons manufacturing by Stark Industries. She was later led from the press conference by Pepper Potts and returned to her mother in the face of massive media backlash.

Her parents eventually began to share custody of her, as her father wanted to take a more active role in her life as he turned over a new leaf in his life after his experiences in Afghanistan, which included helping to raise his daughter. Her mother demanding that it be on a trial basis for at least 6 months, as she was afraid that his desire to be involved would fade and their daughter would get hurt and wanted to ensure he was actually was going to be involved.She began at this point to see her father every other weekend with him having cleared his schedule so he could be free to be with her the entire weekend.

She would often sneak down, during these visits, to the stairs by her father's workshop to watch him work and knew about the suits that he was working on long before he anticipated that she did. Though when she revealed this she told him that his secret was safe with her.

She later would admit that she watched the exchange between her father and his assistant in which Pepper Potts threatened to quit stating that Stark was going to kill himself trying to do right and he convinced her that this was what was right for him to do. When Potts left the room and found the young child sitting on the stairs watching into her father's workshop, she quietly led the child back to bed before she could get in trouble with Stark.

Scientific
She inherited from her father a genius level intellectual ability specifically in the areas of mechanics, engineering, and mathematics. She however has focused primarily on an area that was outside of her father's knowledge, biomedical technology, while still applying the same intellectual ability. By the age of 8 she had grown intelligent enough that she was already beginning to design technology that could heal injuries, admittedly inspired by her dad's frequent brushes with death. She designed leg braces to allow her godfather, James Rhodes, to walk again following a paralyzing injury at only 12 years old.

She created a whole log of offensive and defensive designs that have since been uploaded to her vibranium wrist guards.

Languages
Oneleigh, thanks to classes paid for by her father in her early years and her own practice with langueges she is completely fluent in: French, Italian, Mandarin, Korean, English, Spanish and Portuguese. She was also taught Russian at a basic level by Natasha Romanoff.