Black Widow became a frequent comrade-in-arms of Captain America when they were assigned on missions together. During one rescue mission of a hijacked S.H.I.E.L.D. ship, Nick Fury assigned Black Widow a secret side task to retrieve confidential protected S.H.I.E.L.D. files in a flash drive. The data was more sensitive than she could have guessed, and once it was handed over to Fury he became the target of an assassin. When Romanoff heard that Fury had been gunned down she went to the hospital to keep vigil, and watched helplessly as he was declared dead. Based on Steve's description of the shooter, she identified the killer as the Winter Soldier.