Hulk's Trigger Emotion Isn't Actually Rage, and the Comics Prove It

screenrant.com:

For as long as Hulk has existed in Marvel Comics, it is has been widely believed that Bruce Banner turns into the mighty green giant when anger ignites him. However, what if it was never anger that led to Hulk's transformations but some darker emotion buried far deeper?

The recent Immortal Hulk and many Hulk comics reveal that Bruce has developed multiple personas to combat a brutal childhood. His alternate identities do not appear when he feels anger because anger regularly presents as a secondary, not an initial response. Therefore, it would not make total sense for anger to immediately trigger Bruce into becoming an out-of-control monster. Although there is no question that Hulk's rage makes him a powerhouse, with even the great Thanos afraid to challenge him at one point, the primary emotion that actually prompts Bruce to change is fear.

Related: Marvel Theory: Bruce Banner Will Build A New World Of Hulks

It is not unusual for anger to emerge from fear. People commonly resort to anger to battle discomfort and to control stressful situations, unleashing different and potentially harmful sides of themselves. In Bruce's case, it is understandable that dealing with childhood trauma and head-to-head challenges with powerful villains stems from a place of fear. As a result, his body naturally responds to fright with rage, transforming him into Hulk because Bruce knows his Hulk persona can physically take control of dangerous circumstances.

Bruce is not the only one of his kind to be provoked by fear. In Avengers: The Search for She-Hulk by Geoff Johns and Stephen Sadowski, Jennifer Walter becomes her Hulk form, but Red She-Hulk becomes weaker. She-Hulk unleashes her true powerbut ultimately feels her cousin's same emotion