She laid on the operating table and I sat tensely as Tony fiddled with a computer screen. Tony pressed a button and then there was a hissing sound of pressure releasing and then, literally, a panel lifted from her chest and moved to the side, opening the area over where her heart should have been. She turned her head and beckoned me closer silently. Slowly, I stood and took a step forward, looking into the opening. Inside her chest, looking out of place with all the flesh, blood, and bone, was a metal heart, beating and keeping her alive. I felt her take my hand and I looked at her face.
"Say something." She whispered. I squeezed her hand in mine.
"You're even stronger than I thought."
Mack Lomond, a trusted ally of Agents Hill and Romanoff, is brought in to find and help the Winter Soldier, not because she's the only one who can help, but because she is the only one who can survive him. She has secrets even SHIELD didn't know but she'll have to trust people to be trusted.