Summer is pretty much the intelligence of S.H.I.E.L.D, she's 91-years-old but looks like she's 21, and she's equipped with the brain capacity a human could only ever dream of having. People think she's just a brain, they don't care about her past which is very long and very complicated. She was never prepared for it to get unravelled. Not like this anyway. Bucky Barnes/OC