Natasha spent the entirety of Captain America: Winter Solider trying to take down Bucky, and it looks like the two will face off once again in Captain America: Civil War.
During the Buzzfeed Q&A, Joe Russo was asked a question concerning Natasha's character.
"Anonymous asked: Could you give us more details about Natasha's character in Civil War? Like how will she deal with the big conflict between her good friends, and also her relationship with Cap? What's her point of view on her old enemy, Bucky?"
Russo elaborated on Black Widow's splintered viewpoint and an incoming throwdown between her and Winter Solider.
"She is conflicted. This is her worst nightmare. She sees the value to both sides. Her relationship with Cap is very deep and is a continuation of their story from Winter Soldier. But due to very personal reasons they wind up on opposite sides. She & Bucky definitely have an encounter. :) -JR"
Black Widow has one of the harder choices to make, as she has so much history with the leaders on both sides. Combat wise, her and Winter Solider were plenty entertaining in the last film, and I can't wait to see what they bring to the fight this time I'm Team Cap all the way, but I think Widow has the advantage here.