system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] So, whats up with Hulk "hulking" out when he's angry? Does it mean there are possibilities of it happening in other states of emotion?

Could Hulk have been made in a way that he'd only Hulk when he's extremely happy? Sad? I was just thinking how awful it must be to have depression but then have you hulking mechanism rely on happiness. Keep chugging on those anti depressants.
gpt
Approaching this from the comics, it’s still a little unclear in the MCU:

Bruce Banner had multiple personalizes before the Gamma bomb.  At least as far back as his abuse by his father.    the Gamma Bomb allowed each of these personalities to become the hulk and take over his body, but not all of them are tied to anger. 

-	Grey hulk: at first the Hulk came out at night, and disappeared during the day
-	“Big Guy”/Green Hulk - like the MCU Hulk, this one is tried to anger.  the angrier he gets, the stronger he gets.    he had the personality and intelligence of a toddler, and in many ways represents Bruce retreating back to when he was abused.  
-	Joe Fixit : The reappearance of the Grey Hulk.  Again, tied to night. Intelligent. A little cruel.  Not as strong as the Big Guy.  Worked as a bouncer in Las Vegas for a while. 
-	Professor Hulk: Bruce in Hulks body.  Doesn’t transform.  Bruce at his most balanced. 
-	Devil Hulk : the personality the others are afraid of.  the first hulk persona to kill on purpose.  Big, Green.  Comes out at night.  Takes it real personal if you hurt Bruce. (tied to fathers abuse, again). 



In addition, Ed Norton’s hulk in the MCU seemed tied to heartbeat, not just anger. 


highly recommended runs: Peter David’s run in the 90s

the just finished “Immortal Hulk” by Al Ewing.