Banner is a genius as an expert in the field of gamma radiation. He is overly sarcastic by guessing Hawkeye's joke. After having exposed to the gamma bomb he gained another personality that is monstrous, called the Hulk, that he can change into after his heart rate goes at a certain point by getting too excited or angry. He tries to maintain his heart rate by calming himself down, but it seems that he's able to bring out Hulk by will alone
Banner's personality is that of a kind doctor who likes meeting new people, such as Tony Stark and Steve Rogers, although he is not without a sarcastic side. He is a brilliant scientist whom Tony Stark likes and he makes great work which makes him a great scientist as well. Given that Bruce also sometimes can feel a little upset or angry and depending on what he's feeling. When he transforms into the Hulk then that means he's angry and he's not happy at all. But Bruce is a very nice guy and always helps out, even when it's very difficult for him to fit in with other people. He is known to also be very smart and intelligent and he knows what he's doing when he's performing experiments in his lab or workplace. He is on the same level of genius intellect as much as Stark and Shurui, and Hank Pym
As the Hulk, his personality is the polar opposite to his intellectual self - much like the psychological Id, he is very aggressive, stubborn, and primal, incurred whenever Bruce is angry. Because of Hulk's temper, he causes destruction to his surroundings and beats anything in his path, however, he has a soft spot for animals. After some time, Hulk respected people and had the thought of helping them instead of hurting them, such as when the Hulk rescued Hawkeye's men from a helicopter crash. He can get along with people very well, but can be easily irritated by others if they think that Hulk is only a monster
