A story and its prequel, AU to both the Captain America movies and Agent Carter:
Premise: after the rescue of the 107th, Steve Rogers cashes in all of his favors and makes what deals he can to get Bucky a medical discharge from the Army, sending him home to Brooklyn and far from enemies and curious scientists both. But Steve's war goes on until it ends badly, in an exploding plane over the Black Sea. Captain America is presumed dead, his shield recovered and returned to a grieving America while his body remains undiscovered.
(links to ao3 b/c of story length)
Shielded1500 words | Steve Rogers
1944: Steve at war, sans Bucky.
Preserved72K words | Peggy Carter, Bucky Barnes
1952: a new danger is threatening to unbalance the already-roiling Cold War: a Soviet assassin let loose from behind the Iron Curtain. Peggy Carter isn't sure she wants to believe that the assassin is a super-soldier because of what it could mean, but she does know that whoever it is, she'll have to break her promise to keep Bucky Barnes far from danger.