I'm always angry.

Disclaimer: I never got into the comic books. This is based only on the last decade and a half of movies.

When The Hulk was first created, Banner feared it because he didn't know how to control it. It could kill people, destroy military vehicles, wreak absolute carnage. And he was scared because he didn't know how to stop himself once he got started. His anger would click on, and it was over from that point forward.

At the end of the Edward Norton version (2008), he escapes into the wilderness to figure shit out.

The character is noticeably different when he shows up in The Avengers (2012). Sure, this could be due to Ruffalo's unique interpretation, but I think there's more going on.

Banner is more pensive, mature. Its obvious he's been through shit, and probably not just the physical kind. He has character.

In the final battle, its revealed that he has learned how to harness his anger and use it when he needs it. And surprisingly, this makes Hulk more personable.

In Stoicism we are essentially told to use our emotions like we use tools. To get something accomplished. You're depressed? Pissed? Elated? Jealous? Insecure? Scared? Examine why and adjust your path accordingly. U/sexyshoulderdevil put it well recently. The goal is not to become emotionless, but appreciate them for what they are with the preemptive understanding that they are shifty as fuck. No decisions of any importance should be made based on them, but they are great fuel.

There's a reason we tell every pissed off little man-child to spend that rage on the barbell.

When you're hungry, do you obsess over your hunger, focus on the feeling of your stomach gnawing on your backbone, and sit around hoping something will change? No. You get the fuck up and eat a steak. Likewise, emotions are signals that, in an actualized man, should 1) be appreciated and 2) prompt action. Nothing more, nothing less.

Another point. There are dozens of guys in these parts - myself, archwinger, and others who have long-lasting, latent, or simmering anger over the blue pill lies we've been fed. Its completely justified. There's a reason the "anger stage" is a thing. It provides that catalyst that makes newb gains really fucking easy to achieve. But what do you do with anger that lasts a year, two, three, or ten? That simmering resentment?

Use it to make your world your bitch.

Aside, I think Ruffalo aced the role, especially compared to Norton.