Head Canons

Over time, as Bruce gains control over his ability, Hulk will begin to gain intelligence, so his speech will improve.
Bruce is emotionally repressed, but slow to opening up (unless he’s on edge, he’ll talk a mile a minute).
He doesn’t want to get close to people in the case that he hurts them despite his desire to be close to someone. It’s safer this way.
Not necessarily asocial, but withdrawn and unable to properly interact with people for long stretches of time.
When nervous, he speaks a lot.
He’s still resentful of Hulk, so he keeps him locked up
When he’s doing his breathing exercise, he becomes self-conscious. He feels weird doing them when people can see him.
He blames himself for a lot of things.
He can’t keep still unless he’s doing work, he fidgets.
When he’s working on something, he tends to close off everything but the work. He can and will go hours doing research and experimenting whilst ignoring his body’s needs.
The angrier Hulk gets, the stronger he becomes
He’s into sustainability (improved organic and friendly farming, renewable energy, eating locally), politically, Bruce can be considered a socialist liberal—he thinks the OWS movement is a good idea, but very poorly executed
He knows Spanish, (Brazilian) Portuguese, Latin, Malay, Punjabi and Bengal (with some Russian due to working with a Russian physicist on a project before).
Despite his size, he’s quite strong due to the conditioning from yoga and capoeira angola (which he practiced in Brasil)
He goes off on tangents because he forgets the brain-to-mouth filter and says his thoughts aloud (it lets you know if he’s on topic with what you’re saying—he usually isn’t)
He sleeps with his glasses on sometimes and tends to talk to himself (or Hulk if he has to)
If he focuses enough, he can talk to Hulk (and hear Hulk) without changing. However, when Hulk is in charge, he can only get glimpses and feelings of what is going on.
He can be funny. Sometimes. He hopes.
Sardonic, pessimistic (Realist!), and self-deprecating