Shannon Carter is the cousin of S.H.I.E.L.D. agent Sharon Carter, who grew up idolizing Captain America. She got a job working as a tour guide for the Avengers Mansion. When the new Avengers team was formed, she was invited to join. She had designed a costume, created disc weapons that looked like miniature versions of Captain America's shield, and underwent a lot of physical training to make herself as strong and as agile as humanly possible.