Peggy Carter's great-niece, who did everything the way her aunt did and found out that nobody was coming to help her.
Sharon Carter is the great-niece of S.H.I.E.L.D.’s founder Peggy Carter. She follows her aunt into the agency and takes the codename Agent 13. On Fury’s orders she watches over Steve Rogers as an undercover nurse, and then helps him bring down a S.H.I.E.L.D. that Hydra had been inside for seventy years. She joins the CIA afterwards, and goes into hiding after helping Rogers during the Avengers’ civil war.
Then the films leave her there. She survives the Blip in exile, unpardoned, while the people she helped are celebrated.
Minor spoiler
By the time of The Falcon and the Winter Soldier she has established herself in Madripoor as the Power Broker, running the city’s criminal underworld. She is pardoned and reinstated at the end of the series without anyone finding out. The turn divided viewers, and this catalogue notes that the reaction to the character was generally positive and the reaction to this specific development was not.