Winter Widow

Winter Widow is the het ship between Natasha Romanoff and Bucky Barnes from the Captain America fandom.

Moments

 * In Captain America: The Winter Soldier Natasha tells Steve that she knew the Winter Soldier, but she didn't knew then that it was Bucky
 * In Captain America: Civil War Natasha and Bucky fight while he's under brain washing, she asks him if he would recognize her
 * In Captain America: Civil War we can see Bucky taking Natasha's gun in Syberia, he still has it in Avengers: Infinity War.

Fanon
People like the ship because of their involvement in the red room, as well as the way their personalities interact. Natasha is portrayed as stoic and Bucky is portrayed as the guy you don't cross, according to the fans, this ship is canon in the comics.

Fandom
AO3