Bizarre Things About Hulk And Black Widow's Relationship

The Hulk's departure at the end of Age of Ultron wasn't exactly a mystery, though the question of why he did it was never precisely answered either. There were plenty of reasons for him to go. Whatever his reason was, at the time it seemed unselfish. It seemed like he was doing it for Romanoff and his friends in the Avengers at least as much as he was doing it for himself. But the events of Thor: Ragnarok shine a brand new light on the end of Age of Ultron.

We know that Hulk failed to change back to Banner for two years after Age of Ultron. We also know that for most, if not all, of that time Banner had no control. He tells Thor that in the past, he'd felt like both he and the Hulk had some control over their actions as the Hulk, but that for the two years between Age of Ultron and Ragnarok the Hulk was solely in control and that Banner had been "locked in the trunk."

If that's true, it wasn't Banner's choice to leave Romanoff, the Avengers, and Earth. It was the Hulk's choice. And if that's the case, then it seems clear he did it to remain the Hulk.

We know Black Widow had figured out a way to "lullabye" Hulk back to Banner. We know it was the video recording of Black Widow that triggered Hulk to finally change back to Banner in Ragnarok. So it may be that, ironically, while it was Natasha who pushed Banner down the hole and summoned the Other Guy, the Other Guy left Earth not in spite of Natasha, but because of her. Because he wanted to remain the Hulk, and he didn't want puny Banner's bizarre relationship with her to put him back to sleep.