Gaaah, I read one once that I can't remember enough details to find. It involved Bucky in TFA doing everything in his power to avoid becoming the Winter Soldier--like refusing to join the Commandos, taking extra precautions on the train, etc.--but everything he did set off a butterfly effect that resulted in Hydra winning. Maybe somebody else knows it?

Anyway, I was searching in vain and happened to run across this, which is also good: I can’t remember how this started (but I can tell you exactly how it ends) (http://archiveofourown.org/works/2658254) Steve/Bucky