Bruce had never known life without anger.
For as long as he could remember, his father had hit his mother and threatened Bruce because he thought Bruce's mother loved Bruce more than she loved him. He didn't wonder why that was true.
Then there was anger at himself. For not waiting until he knew the experiment was safe to test. Because of all the people who had suffered and died because of him.
He kept it at bay, mostly. The fact that it was always there, like white noise, made it easier to ignore.
But he was always, always angry.