Pietro and twin sister Wanda were born in the country of Sokovia. Their family used to reunite and watch american sitcoms together while trying to momentarily forget that they were living in a warzone. One night, when the family was gathered before the TV, a mortar shell hit their house, killing Wanda and Pietro's parents. Pietro and Wanda survived and hid under the bed just as a second shell hit, but it did not explode, leaving twins where trapped for two days before being rescued.
Years later, Pietro and Wanda started to participate in riots in a attempt drive the foreign forces out of their country. However, they twins did not know that these riots were actually planned by HYDRA, as the organization used them to cover in their illegal experiments after they secretly established in the country. Sometime later, a HYDRA scientist approached the twins to offer the opportunity to get enough power to drive war out of Sokovia. His sister Wanda was skeptical about the offer, but Pietro was not since he was determined to free Sokovia, so he convinced his sister to accept it. As results of these experiments, Pietro achieved superhuman speed while Wanda won numerous mental powers as telekinesis, hypnosis, and energy projection.
Personality
Quicksilver is fun-loving, kind, caring, serious, moral, honorable, selfless, and intelligent. However, he is also shown to be slightly overconfident, arrogant, impatient, tenacious, and short-tempered. Compared to his twin sister, Wanda, Pietro was far less quiet and far more aggressive. As Wanda is the only family he has left after the death of their parents, he is very protective over her and also a caring sibling. Ultimately, Pietro shows to be very reckless yet heroic. He uses his own body to shield Hawkeye and a civilian boy from the Quinjet's bullets, proving himself a true hero and a true Avenger, before dying from his wounds.
Powers and abilities
Powers
Superhuman Speed: Quicksilver can move at extremely high, even supersonic speeds. He can move so fast that he looks like a blur.
Extreme Force Generation: Due to his speed, Quicksilver's momentum allows him to enhance the force in his attacks, strikes, impacts, and collisions, often propelling objects or people several feet, that he uses to compensate for his average human strength.
Accelerated Perception: Quicksilver's speed extends to his senses and mental capacities, able to take in information and process it just as fast, allowing him to see the world as if it is in slow motion, which combined with his physical speed lets him think, perform actions, react to events, long before anyone/anything can even perceive or detect him. He has perfect control over this ability, he is not always seeing the world in slow motion.
Supercharged Brain Activity: Quicksilver can access superhuman levels in his brain further than processing information. He can test theories, understand difficult equations, run trial and error in his brains at superhuman speeds, and permanently remember and instantly recall everything he has read, seen, or heard without trouble.
Superhuman Agility: Quicksilver's speed extends to his agility, as he is far more flexible and had greater balance than a normal human.
Speed-Induced Resistance: Quicksilver can resist the effects of friction, reduced oxygen, and kinetic impact while moving at incredible speeds.
Superhuman Metabolism: Quicksilver has a hyper-accelerated metabolic rate, enhancing his body, physicality, senses, brain, mentality, and power to move and act while also making him less able to be stunned by attacks or injuries.
Superhuman Reflexes: Quicksilver's speed extends to his reflexes, allowing him to react to danger and events much faster than a normal human. His reflexes are so fast that they even allow him to catch bullets in mid-air.
Bodily Vibration: Quicksilver has the ability to vibrate most or all of his cells and overall parts of his body on command for various effects.
Abilities
Expert Hand-To-Hand Combatant: Quicksilver is extremely skilled in hand-to-hand combat. His fighting skills combined with his intelligence, superhuman speed, and reflexes, make Quicksilver a formidable opponent alone in single combat.
Bilingualism: Quicksilver is capable of fluently speaking English and Sokovian.
Pietro and his twin sister Wanda participated in a series of experiments conducted by HYDRA in hopes of saving their country, Sokovia, from war. As results of these experiments, Pietro achieved superhuman speed; while Wanda won numerous mental powers like telekinesis, hypnosis, and energy projection. In the mid-credits scene, Quicksilver and Scarlet Witch appear with Baron Strucker at a facility in Sokovia. Strucker also revealed he intended to use them for an unspecified purpose.
Soon after, the Avengers arrived in Sokovia and raided Strucker's facility, stealing the scepter and arresting Strucker. In the confusion, Scarlet Witch and Quicksilver escaped from their holding cells and, though inexperienced, were able to use their powers to evade the Avengers and escape. Quicksilver himself used his powers to distract Hawkeye and Captain America, using his speed to try to stop their advance and to protect a bunker, which is destroyed by the Hulk soon after. When Tony Stark took the scepter, he tried to stop him but was stopped by his sister. He asked why, but she just smiled.
Scarlet Witch and Quicksilver were soon called by Ultron to join him in his plans to destroy the Avengers, knowing that with their powers, they can tear the opposition apart. He told Ultron why not just kill the Avengers, Ultron replied that he did not want them to be martyrs. Soon after, Scarlet Witch and Quicksilver accompany Ultron in acquiring Ulysses Klaue's supply of vibranium. When the Avengers arrived, Quicksilver attacked Captain America, then Thor trying unsuccessfully to use Mjølnir against him. When Scarlet Witch attempted to "hex" Hawkeye - but was subdued by him because he learned from his past experience of being mind-controlled by Loki. Quicksilver saved her in the nick of time. He took her outside Klaue's base, where she caught sight of the Hulk and manages to "hex" him as well.
When the twins arrived in Seoul, Wanda learned of Ultron's plans upon touching the Cradle and they left the facility, much to Ultron's rage. The twins then assisted Captain America in fighting off Ultron on a moving passenger train. Scarlet Witch managed to stop it when it went off the rails, while Quicksilver saved people on the road of the train. The twins then accompanied Captain America back to Avengers Tower and tried to stop Stark and Banner from bringing Vision to life. Quicksilver succeeded to cut off the electricity from Vision's cradle, but he is soon attacked by Hawkeye, only to witness Thor bringing Vision to life. He and Scarlet Witch then joined the Avengers in stopping Ultron and saving Sokovia.
He along with his sister, Vision, and the Avengers traveled to Sokovia to stop Ultron and prevent his plan was a success. Before the battle, Quicksilver went to a police station and asked them to help evacuate the city. Quicksilver bravely uses his powers to save countless lives. When his sister volunteered to guard the key against Ultron, he asked her if she was sure of it, she replied to go and come back for her when the battle ended. He uses his own body to shield Hawkeye and a civilian boy from the Quinjet's bullets, proving he was a true hero and a true Avenger. Unfortunately, Quicksilver dies from his wounds, much to his sister's sorrow. His sister avenged his death by ripping out Ultron's metal heart. After the battle, his fellow Avenger Hawkeye named his newborn son Nathaniel Pietro, in honor of him.
In the third episode of the series, Pietro is referenced by Wanda, when she discloses to Geraldine that she is a twin, after giving birth to twins of her own. Geraldine then recalls his demise at the hands of Ultron.
Agatha Harkness later controls Ralph Bohner to portray Pietro, so she can manipulate Wanda. She has him pose as her deceased brother, and he briefly integrates himself into her family, acting as uncle to her sons, before Wanda rejects him, after coming to realize he's an impostor.
In the eighth episode, Agatha reveals that the "fake Pietro" is the result of a "crystalline possession" because she would not be able to manipulate the real Pietro with necromancy and bring him to Westview, because he is on another continent, "full of holes" and her magic has limits. Later, when Wanda and Agatha are watching Wanda's memories to find out how the Hex was created, they see Wanda and Pietro as kids along with their parents in Sokovia. The family watches sitcoms together when a Stark missile hits their house, killing Wanda and Pietro's parents. Wanda and Pietro hide under the bed when a second missile hits the house, but it does not explode, leaving the twins trapped for two days. During another memory, Wanda and Vision are seen talking about Pietro at the Avengers compound, sometime after his death. Vision tries to comfort Wanda for her loss, but Wanda replies that the only thing that would give her comfort would be seeing Pietro again.
X-Men Cinematic Universe
Another version of Quicksilver, named Peter Maximoff appears in the X-Men Cinematic Universe, portrayed by Evan Peters. The Quicksilver in those films is a completely separate adaptation of the character from the one featured in Avengers: Age of Ultron, with his name changed to "Peter", on account of being born and raised American.
X-Men: Days of Future Past
After Logan goes back in time to 1973, he recruits Quicksilver, to help break Magneto, out of the pentagon.
Deadpool 2
Quicksilver, along with a few other members of the X-Men appear in a brief cameo. They can be seen conversing in another room, while Wade is in the X-Mansion, complaining that the studio hasn't allowed them to bring in one of the more famous members of the team.
Quicksilver returns, albeit briefly, when he aids the team in rescuing the astronauts in space at the beginning of the film. During the mission, Jean Grey absorbs the Phoenix Force which begin to have an effect on her mental health and powers. When she goes to confront her father back at his home, Quicksilver is among the X-Men to try and bring Jean back to the mansion. A fight breaks out after Mystique is killed and, despite his speed, Quicksilver ends up getting tossed aside and severely injured. He does not reappear until the end of the film where he has made a full recovery, though jokes that he could have healed a lot faster.
There are notable differences between Quicksilver in the MCU and in the original comics.
In the comics, Quicksilver is a Romani-Jewish man. In the films, Quicksilver was cast as a white man with the character's Romani ethnicity being erased and his Jewish culture being unmentioned but likely absent.
Him having been Romani-Jewish in the comics was a vital part of his backstory in the comics as even in modern Europe, Romani peoples and those of Jewish faith are often discriminated against and ostracized.
While he was originally a super-villain subordinate in the comics, in the comics he was originally a member of the Brotherhood of Mutants. The Brotherhood of Mutants being a group of mutants lead by Magneto who fought against the government in hopes of achieving equal civil-rights. In the films he was made into a member of HYDRA, a group of neo-nazis (again contributing the the erasure of Quicksilver's Jewish/Romani heritage in the films).
Aaron Taylor-Johnson's mid-credits role in Captain America: The Winter Soldier was uncredited.
Despite his character's death, Aaron Taylor-Johnson is contracted to reprise his role in future pictures. This led to fan speculation that his character would be revived in Infinity War. However, Marvel producer Kevin Feige has stated that Pietro is permanently dead.
In Age of Ultron, Quicksilver and Scarlet Witch were portrayed as brother and sister. Ironically, in the 2014 film Godzilla, Aaron Taylor-Johnson and Elizabeth Olsen's characters, Ford and Elle Brody, are portrayed as husband and wife.
The actors who portray the two Quicksilvers (Aaron Taylor-Johnson and Evan Peters) appeared together in the movie Kick-Ass, which was a superhero movie based on a comic book by Icon, an imprint of Marvel Comics.
Evan Peters portrayal of Quicksilver has an Americanized name in X-Men Movies: Peter Maximoff.
In the WandaVision series, despite the Pietro in Westview and the Quicksilver from the X-Men films being played by the same, which caused many to believe that they were the same character, the eighth episode reveals that Pietro in Westview is an actual person who was the result of a "crystalline possession" who acted as Agatha's eyes and ears.
This had already been hinted when Agnes revealed herself as the witch Agatha Harkness in the seventh episode and the one responsible for bringing Pietro to Westview, implying that he is actually someone else pretending to be Wanda's brother, instead of the Quicksilver from the X-Men films.
In seventh episode, this is also hinted when Wanda tells Billy and Tommy that this Pietro is not their uncle, when Vision calls him "impostor" and when "Pietro" captures Monica Rambeau during the post-credit scene.
The costume Fake Pietro wears for Halloween in the sixth episode of WandaVision, is the spitting image of his comic book costume.