Bruce Banner (2008)

"That's my secret Cap, I'm always angry."

- Banner to Cap

Bruce Banner is a genius scientist who, due to exposure to Gamma Radiation transforms into the Hulk when his heart beats at unhealthy speeds.

The Incredible Hulk
"I can't control it... But maybe I could guide it, aim it in the right direction."

- Banner to General Ross and Betty

Bruce Banner was experimenting to make humans immune to Gamma Radiation, but when testing the experiment on himself, he transformed into the Hulk and hospitalized his lover, Betty Ross and injured her father, General Thaddeus Ross (who was hoping Banner would perfect his serum in order to re-create a super-soldier serum). Now a fugitive from the United States Army, Banner works in a soft drink bottling factory in Brazil while attempting to find a cure for his condition with the help of an Internet friend known to him as "Mr. Blue". To prevent another transformation, Banner undergoes rigorous meditation and keeps his pulse at a steady level.

After Banner suffers a cut, a drop of his blood lands into a bottle of soft drink eventually drank by an ill-fated consumer. Following the event, Banner is compromised and General Ross sends Emil Blonsky and a special forces team to apprehend him. While trying to evade the special forces, Banner is attacked by thugs and becomes the Hulk. The Hulk fights off the thugs and the special forces team and escapes leaving Blonsky unharmed. Banner wakes up in Guatemala, dazed by the experience and eventually makes his way to the United States, where he sees that a now-recovered Betty is working at Culver University and is dating psychologist Doctor Leonard Samson. He also sees his old friend Stanley, a pizzeria owner, who gives him a job as a delivery boy. Banner uses this job to sneak past a Culver University security guard to continue his research. One night Betty visits the pizzeria, and sees Bruce, later reuniting with him.

Blonsky reports to Ross that Bruce evaded them in Brazil because of the appearance of a large green monster. Ross explains that the monster is Banner, and that he was created accidentally during an experiment in radiation-resistance that, unbeknownst to Banner himself, was inspired by World War II (WWII)-era military bio-force enhancement research, (or "Super-Soldiers", as Blonsky puts it). Blonsky, seeking both revenge and power, volunteers as a test subject in order to capture Banner, and receives a small dose of of the mothballed original super-soldier formula made in WWII by Dr. Reinstein. He leads an assault on Banner at Culver University, during which Betty is knocked unconscious. Despite Blonsky's increased strength, speed and agility, the Hulk crushes most of the bones in Blonsky's body before absconding with Betty to Smokey Mountain National Forrest. Banner and Betty then travel to Manhattan, where they meet Banner’s "Mr. Blue" Internet friend, Dr. Samuel Sterns. Accompanying Sterns to his lab, Banner and Betty learn that Sterns has developed a possible antidote that may reverse Banner's transformations after their occurrence but might not prevent future ones, while an overdose would possibly kill him. Despite the risks, Banner agrees to test Sterns' antidote and is restrained before being shocked into transforming with electricity and then reverted to normal with an injection of the serum and Betty's calming words. Exhilarated by the success of the antidote, Sterns reveals that he has synthesized Banner's blood sample into a large supply with the intention of using it to enhance the human condition to the next evolutionary level. Appalled by what his colleague had committed and fearful of the the Hulk's power falling into the wrong hands, Banner attempts to convince Sterns to destroy the blood supply when he is shot by a tranquilizer from one of General Ross' snipers.

As both Banner and Betty are taken into custody, Blonsky, whose super-soldier treatment has healed all his injuries but is desperate for more power, confronts Sterns and demands he subject him to a dose of the Banner's Gamma Radiation treatment. Sterns warns that the combination of the super-soldier serum and a gamma treatment would be an unpredictable combination and could turn him into an "abomination." Blonsky however is less than concerned about the possible consequences and Sterns promptly administers the gamma charge. As Blonsky mutates into a hideous titan, he knocks Sterns aside and an irradiated sample of Banner's blood-derivative drips into an open wound on Sterns temple, causing his cranium to mutate and expand as the Abomination goes on a rampage in the city, hoping to draw out Banner. Banner, realizing that he is the only one who can stop the Abomination, convinces General Ross to release him. He jumps out of Ross' helicopter as it hovers over the city, hoping the fall will stimulate his adrenal glands into triggering a transformation. Banner's plans succeeds and after a violent, pitched battle; the Abomination is defeated when the Hulk brutally strangles him with a huge chain but is stopped from killing him by Betty. After winning the battle, the Hulk flees the scene with the army in hot pursuit.

Thirty one days later, Banner is in Bella Coola, British Columbia. Instead of trying to suppress his transformations, he is attempting to initiate them in a controlled manner. As his eyes turn green, a grin appears on his face.

Thor
Bruce was mentioned by Erik Selvig and he declared he once knew him as a pioneer in Gamma Radiation until S.H.I.E.L.D. showed up, and he hadn't been heard from since.

The Consultant
According by Phil Coulson, General Ross and the World Security Council blamed Banner for the Battle with Blonsky.

The Avengers
"We're not a team. We're a time-bomb!"

- Banner to The Avengers

Once again on the run, Banner found a new direction for himself acting as an unregistered physician helping people in poverty-stricken slums. No longer obsessed with finding a cure for himself, he had gained peace of mind in helping others. One night while working, he found himself lured into a meeting with Natasha Romanoff, an agent of S.H.I.E.L.D., who proposed a job for him helping S.H.I.E.L.D. with a dire emergency. Initially dubious, and suspecting that S.H.I.E.L.D. was really after his green alter-ego, Banner resisted, but eventually he relented and agreed to Romanoff's request.

His assignment on the S.H.I.E.L.D. Helicarrier was to track the location of the Tesserect, an object of limitless power that had fallen into the possession of Loki. He worked together on this project with Tony Stark, the industrialist also known as "Iron Man", and was introduced to others, who like himself, were also more than human. Almost immediately, the clash of personalities within this assembled group provided a constant source of tension for all and Banner was subjected to frequent reminders of his need to contain the beast within. When others of the group apprehended Loki, and the Asgardian was imprisoned on the carrier, the antagonism only got worse.

The Hulk finally boiled to the surface again when Clinton Barton, a S.H.I.E.L.D. agent under Loki's control, led an attack against the carrier. Explosions from the attack caused debris from the ceiling to rain down on Banner, injuring him and triggering the change. He first rampaged around the vessel hunting Agent Romanoff, before turning his attention on Thor on the hangar deck. Finally, a S.H.I.E.L.D. pilot in a fighter jet outside got his attention by shooting him through a window, causing the Hulk to leap out and fall.

Banner awoke in the blasted remnants of a warehouse and was immediately greeted by a lone security guard who offered him clothing. He was also relieved to learn that nobody else had been around when he crashed down.

Following disturbances into New York City, where Loki had opened a dimensional rift, Banner located his superhuman acquaintances assembling to counter the threat. Although they were wary of another transformation, they insisted that he would be a help. Banner obliged, triggering a controlled transformation, then together with the others, he turned his attention on the Chitauri invasion force pouring through the portal. The Hulk did indeed prove to be an asset to the group. Not only did he single-handedly kill the first of the Chitauri leviathans that came through the portal, he was an unstoppable force in dealing with individual alien warriors, and instrumental in capturing Loki.

Long after the battle was over, Banner, now back to normal again, gathered with the others to see off Thor and the captive Loki. The threat had been neutralized and for a time the world would have little need of its protectors. Banner and the remaining heroes said their goodbyes and parted company.

Personality
Banner is always in a state of controlled rage and if he's not He isn't Banner but instead the Hulk.

Powers
Banner only has one superhuman power. Transformation: Previously Bruce would transform into the Hulk, when he would lose control of himself because of rage or adrenaline, stress, which hormonally stimulates the heart rate. The total time of transformation takes only seconds. Banner became the Hulk with increase in heart rate or adrenal levels, suggesting that the true trigger mechanism into the Hulk is far more psychological than physical. When the Hulk transforms back into Banner, the excess muscle mass and energy is lost, presumably to the same place he derives it.
 * Banner was unable to control the transformations, but through training and practice had managed to attain some level of control. Banner's consciousness is buried within the Hulk's, and can influence the Hulk's behavior only to a very limited extent such as when he changed into the Hulk to fight the Abomination where he managed to possess some human traits when asked by Betty Ross not to kill his enemy. Hulk also prevented an explosion from killing Betty and carried her to safety.
 * After over a year of training to control the Hulk, Banner learned that if he always remains angry in a controlled state then he can easily change into the Hulk at will. This Hulk appears to be much smarter and less enraged. Taking orders from Captain America and calling Loki a "Puny God".
 * However, if Bruce is sent into a state of stress then he can still lose control and transform against his will despite trying to control it. This Hulk seems to revert back to a savage enraged state where he would attack anyone being friend or foe.

Abilities
Super Genius Level Intellect: Banner is a gifted scientist: there's no one that knows Gamma Radiation like he does and, according to Tony Stark, his work on anti-electron collisions is unparalleled. Agent Coulson compares him to Stephen Hawking.

Plausible Martial Artist: Banner spent a while in Brazil learning Brazilian jujitsu.
 * Breathing Exercises: Banner spent a while in Brazil learning breathing exercises.

Strength Level
Average Human Strength: Banner can lift at least his own body weight.

Relationships
Hulk - Alter-ego

Lover

 * Betty Ross - Love interest

Friends

 * Leonard Samson - Friend

Teammate(s)

 * Steve Rogers - Avengers teammate and leader
 * Tony Stark - Avengers teammate
 * Thor Odinson - Avengers teammate
 * Natasha Romanoff - Avengers teammate
 * Clint Barton - Avengers teammate

Ally( y - ies)

 * Dr. Erik Selvig - Ally
 * Nick Fury - Ally

Enemies

 * General Thaddeus Ross - Enemy
 * Emil Blonsky/Abomination - Enemy
 * Dr. Samuel Sterns - Enemy
 * Loki Laufeyson - Enemy
 * Chitauri - Enemy

Appearance/Actro(s)
Marvel Cinematic Universe (2 movies)
 * The Incredible Hulk (first appearance)  - Edward Norton
 * The Avengers - Mark Ruffalo