Originally known as Jack Harrison, Jack Flag was a member of Captain America’s computer hotline network along with his brother Drake. In a fight with Mr. Hyde, Flag was doused in Hyde’s chemicals and developed superhuman abilities as a result.
During the Marvel Civil War, Flag was targeted by the Thunderbolts for violating the Superhuman Registration Act. During an entanglement with Bullseye, his spinal cord was punctured, effectively paralyzing him from the waist down. Flag was imprisoned at 42, until his appearance in Guardians of the Galaxy.
His superpowers include superhuman strength, speed and stamina.