Winter Soldier raises Tony Stark (AU)
When Bucky Barnes is sent to kill the Starks, he does so easily until he sees their baby son in the back seat. Unable to kill him, he escapes with the child.
Living a life on the run, Bucky slowly breaks out of his Hydra conditioning and raises the boy as his own. As Tony grows, their bond only grows stronger, even as Bucky stops ageing.