headcanon that Natasha’s an amazing singer but God help the poor fool who every comments on it. Everyone knows this. You mention the singing, you die. Fact.
Everyone knows but Bucky. And one day Bucky hears her singing Russian lullabies to herself and softly joins in, because he still remembers the language, and Natasha lets him. And Clint stumbles into this bizarre assassin duet and just backpedals the fuck outta there because nah man, there’s some things he’s just not prepared for, and the two scariest people he knows singing children’s songs is one of them