Brazil, officially the Federative Republic of Brazil, is the largest country in South America and the Latin American region.
During the time he was considered a fugitive from justice, Howard Stark planned to travel to Rio de Janeiro, spending no more than three days in New York City in order to recover one of the inventions stolen from the vault under his mansion.
Hunt of Bruce Banner
General Thaddeus Ross, responsible of the hunt of Bruce Banner, figured that he could be anywhere in the world, after Banner's track was lost following an incident in the jungles of South America. Ross theorized that Banner he even could be in places such as Paris or Venice.
Unbeknownst to him, Banner traveled to Rio de Janeiro, working in a soft drink bottling factory. The Plant Manager pinpointed that he was the first American he recalled looking for a job in Brazil.
Cure for Gamma PoisoningBruce Banner settled in Rocinha, the largest Favela in Brazil, juggling his job in the bottling factory with attempts to find a cure for his condition. In order to control his emotions and heart rate and prevent his transformations, Banner also studied martial arts and meditative breathing techniques with a Brazilian jiu-jitsu instructor. This lessons allowed him to control and prevent his transformations for five months.
Banner suffered a cut in the factory, and although he ordered to stop the machines to clean it and avoid any contamination, his blood dripped into a soda bottle sent back to the United Stated. Later that same day, Banner noticed one of his co-workers, Martina, being harrassed by a man, and his first impulse was to leave to not lose control of himself. However, his conscience made him approach to peacefully try to drive the molester away. The man confronted Banner, but the Plant Manager appeared and stopped the potential fight between them.
The search for a cure for his condition drived Banner to study a flower described in the book "Inventory of Rare and Endangered Tracheophyta of Amazonia", and he finally received it that day. Banner contacted a man who helped him through his research, codenamed "Mister Blue", to inform him of the discovery. Blue advised him to try a high dose of the component extracted from the plant, and he was able to produce a serum using homemade laboratory equipment.
Banner tried the serum on a blood drop, and while it seemed to be succesful at first, it triggered a reaction that made the cells explode. Informing Mister Blue of the failure, Blue insisted to meet Banner in person, as living with Gamma poisoning could be more dangerous than the eventual risks of their meeting, and convinced him to send a blood sample.
A few days later, Banner received news from Mister Blue, as preliminary blood tests showed significant gamma reduction, but as he asked for more data, Banner realized he should return to Culver University to retrieve it.
General Thaddeus Ross managed to locate Bruce Banner after learning that a man in Milwaukee suffered a severe case of Gamma poisoning after drinking from the bottle that got impregnated with Banner's blood. Ross assembled a military unit led by Russian-born British special operations expert Emil Blonsky, to capture Banner.
Ross and his unit located Banner's house and burst in to shoot him with tranquilizer ammo, but Banner fleed through the window and momentarily hid in Martina's house to deceive the military. Blonsky and the other soldiers pursued Banner through the streets and rooftops of Rocinha, while Banner tried to slow down his heart rate to prevent his transformation.
While fleeing Banner came across General Ross, realizing he was the man behind the chase. He also ran into the molester from the factory, who pursued Banner with his friends to the bottling factory in order to beat him. Blonsky located Banner in the factory and approached to witness the appearance of Hulk, as the transformation was triggered by the men beating him.
Hulk easily knocked out the men, and a ferocious battle between Hulk and Blonsky's team started. Their tranquilizer ammo proved ineffective against Hulk, who finally managed to escape, and Blonsky was the only soldier to end the encounter unharmed.
Ross and Blonsky returned to Banner's house to search for evidences that would indicate Banner's next step, finding a photograph of Betty Ross and Banner's computer. Blonsky asked for the nature of Hulk, and Ross confessed that Banner was that creature, without further details.
São Paulo Mission
Loki tried to taunt Romanoff mentioned some of these events during his time as a prisoner inside S.H.I.E.L.D. Helicarrier. Loki implied that Romanoff caused a bloodshed there while she was trying to interrogate him.
Cybertek sent many of its shipments related to the Centipede Project and the creation of the Deathlok Soldiers to many countries around the globe, including Brazil, in order to hamper their tracking while they were re-routed to the Barbershop Headquarters in Cuba.
Antoine Triplett managed to identify many of them, learning that their destination point was in Havana, letting Phil Coulson and his team guess where John Garrett established his base once he revealed himself as a HYDRA operative.