Bruce and Natasha

"BlackHulk" is the fan-dubbed pairing between Bruce Banner and Natasha Romanoff.

Age of Ultron

 * Both of them mutually like each other, as revealed in Age of Ultron.
 * Natasha used to be scared of the Hulk, but now, is not so afraid of him and even calms him down by touching his hand and soothing the gentle giant.
 * Have kissed each other.
 * Bruce saved Natasha after she was kidnapped by Ultron.

Thor: Ragnarok

 * When Natasha's image appeared on screen when Hulk was attacking the Quinjet, Bruce (as the Hulk) immediately transformed back into himself.