system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Is Hulk in love with Black Widow or is Banner?

She has an uncanny ability to calm down the Hulk and get him to revert into a human.  Is this because Hulk or Banner is in love with her?  Or is she just a really nice lady that can calm world-ending anger in a way that doesn't involve romantic love?
gpt
Bruce and Natasha shared a couple of intimate, awkward moments during *Age of Ultron*, when they were hiding out in Hawkeye's farmhouse. They both have clear feelings for each other, and both think they're too much of a monster to deserve to be loved.

The reason Banner is afraid of that relationship is a factor, too. He's worried that, if they're intimate, he will turn into the Hulk and hurt or kill her. This is a valid fear, since it almost happened in the first *Avengers*.

So when the Hulk sees Natasha, he's seeing the one problem he can't solve by smashing. This is the only time when his anger doesn't serve him. Instead, his rage is replaced with sadness. This is enough to trigger a reversion into Banner.