Captain America

Steve Rogers is a World War II veteran. He was the only successful test subject of Super Soldier Serum. After he was titled Captain America, he was frozen for nearly 70 years which then after he joins The Avengers.

Captain America: The First Avenger

 * "Whatever happens tomorrow you must promise me one thing. That you will stay who you are. Not a perfect soldier, but a good man."
 * ―Abraham Erskine

''Steve Rogers was born in Brooklyn, NY during the Great Depression. His father was a soldier who fought and died in the First World War and his mother became very sick. He had a close friendship with James Barnes, whom he affectionately nicknamed "Bucky". Before WWII Rogers was an artist. After the United States entered the war, Rogers enlisted in the US Army to fight in Europe against the Nazis, but he was rejected for his poor health. Allied German scientist Abraham Erskine admired the spirit and tenacity of Rogers, and kindly signed him up for "Project: Rebirth".''

''"Project: Rebirth" was designed to create the perfect soldier to fight the Axis powers. Rogers underwent regulartory military training and was selected when he proved to be brave, and was willing to sacrifice his life by throwing himself on a dud grenade (which he believed was live). The experiment was successful and Rogers was pushed to the peak of human ability. After the operation, a Hydra sabuteur, called Heinz Kruger, assassinated Erksine and henceforth prevented the creation of any more super-soldiers. Rogers felt passionate about Peggy Carter, an English military officer overwatching his progress. He was denied recruitment into the army and was used as a propaganda tool, until he saved Allied soldiers from imprisonment under his nemesis, the Red Skull.''

''Rogers would later assemble a team, the Howling Commandos, to battle HYDRA across Nazi-occupied Europe, during which his friend Bucky fell to his supposed death. A final battle with HYDRA in the Alps saw Captain America's final struggle with his nemesis, who essentially dissappeared when grasping hold of the Tesseract, a mysterious powerful artifact allegedly forged by the Asgardians. Rogers crash-landed the Red Skull's jet into Antarctica before it could destroy cities around the world, leaving him preserved in the ice for almost seventy years.''

''After seventy years, Rogers was defrosted and kept in a simulated 1940s environment to try and ease him into what was happening. When he awoke he quickly realised it wasn't real and escaped into the streets of a 2010's modern day Manhattan New York. In Time Square, Rogers encounters Nick Fury who tells him that he's been "asleep" for nearly 70 years.''

The Avengers

 * "I hope I'm the right man for the job."
 * ―Steve Rogers

''A week after being defrosted, Steve Rogers found himself lost in a world that has moved on without him and found it very difficult to adjust to this modern world. While working out in a boxing gym in the middle of the night, hitting a punching bag, Steve recounts various events that took place during his era in the war including his fight against HYDRA with his allies the Howling Commandos, Bucky's death, his last fight with Red Skull, his sacrifice, his last conversation with Peggy, and being defrosted. These memories infuriated Rogers to the point he used all of his super strength to break the punching bag. At that moment Nick Fury approached him with a mission to save the world.''

''Fury informed him that a being known as Loki had stolen the Tessaract and intended to use it to conquer and rule the Earth. Rogers wasn't thrilled to learn that HYDRA's secret weapon and power source had found its way into this era. Rogers accepted the assignment and Fury asks him to reveal any more useful information regarding the cube that he might be aware of, to which Rogers claimed "that they should've left it buried in the ocean".''

''On his way to the main S.H.I.E.L.D.headquarters, while aboard the Quinjet, Rogers was debriefed by Agent Coulsen about a selected group of people that were chosen to be apart of the Avengers Initiative. One member in particular that intrigued Rogers was Bruce Banner aka: The Hulk. Coulson revealed to him that Banner attempted to recreate Erskine's Super Soldier Serum believing low levels of Gamma Radiation was a key ingredient in the formula's properties. However when he was exposed to high levels of Gamma Radiation he transformed into the 8 foot tall powerhouse behemoth known as the Hulk. Coulson and Rogers shared an awkward moment when he revealed that he watched Rogers being defrosted and expressed with great enthusiasm how much of an honor it was to have Rogers on board to lead this team. Rogers was some what skeptical of himself being the right candidate to lead but Coulson reassured him that he is and that he's personally overseen the development of a newly constructed uniform for him with some design input from himself. ''

''Rogers was surprised that he would be wearing his trademark stars an stripes since in this modern era it would appear to be outdated and old fashioned. Coulson reassured him that with the enormous threat they were about to face, people would need an old-fashioned symbol to inspire them with hope.''

''Once arriving on the S.H.I.E.L.D. Helicarrier, Rogers meets Natasha Romanoff and Bruce Banner. Inside the Helicarrier, Fury informs Rogers that Loki had been located in Stuttgart, Germany. Roger's immediately suits up into his new uniform and heads off to Germany with Natasha aboard the Quinjet.''

''Upon arriving in Germany at a Gala, Rogers uses his shield to deflect an incoming blast from Loki's staff weapon upon an elderly man who refused to kneel before Loki who was trying to enslave a crowd of citizens. Rogers then engages in a fierce battle with Loki and despite his disadvantage against the "God of Mischief" manages to hold his own against him long enough just as Iron Man arrives on the scene. Loki seemingly surrenders easily.''

''On routh, back to the Helicarrier aboard the Quinjet. Rogers reveals to Stark that he's very uneasy with Loki's surrender as he doesn't remember it ever being that easy. Stark openly mocks Rogers. Suddenly a mysterious thunder and lighting storm appears in the Quinjet's path which Rogers sees that it has frighten Loki. Without warning Thor appears and promptly grabs Loki before he flies away. Stark immediately pursues them and despite Black Widow advising him to sit it out as its way too dangerous for him. Rogers proceeds to sky-dive after both of them.''

Trivia

 * In Iron Man, a prototype of Captain America's shield is visible in the background in the scene where Pepper Potts discovers Tony Stark is Iron Man.