Quicksilver

"You didn't see that coming?"

- Pietro Maximoff to Hawkeye

Pietro Maximoff was a native of the Eastern European country of Sokovia who grew up with his twin sister, Wanda. The country, which was embroiled in constant war and strife, became the base of operations for a HYDRA cell operated by Baron Wolfgang von Strucker, who recruited Pietro and Wanda to take part in a series of tests involving the Scepter. The tests gave the twins superpowers; while his sister Wanda received a number of mental abilities; Pietro acquired the ability to move at supersonic speeds and other physical features. When HYDRA fell, the twins joined the robot Ultron to get their revenge on Tony Stark, but eventually switched sides and joined the Avengers when they discovered Ultron's true intentions.

Early Life
"Wanda and Pietro Maximoff, twins. Orphaned at ten when a shell collapsed on their apartment building. Sokovia has had a... rough history, it's nowhere special but it's on the way to everywhere special."

- Maria Hill and Steve Rogers

Pietro Maximoff was born in the Eastern European country of Sokovia along with his twin sister, Wanda. At the age of ten, while having dinner with his family, a mortar shell hit their apartment building, killing Maximoff's parents and trapping him and his sister. A second shell hit the apartment near them but did not go off; the Maximoff twins were left trapped for two days staring at the unexploded shell reading the name on it, Stark Industries. This traumatic experience gave the twins a great hatred for America, especially Tony Stark and later the Avengers. They often took part and led protests against the Avengers. They dedicated much of their lives to his hatred and began searching for ways to bring down the Avengers; this constant political activity put them on S.H.I.E.L.D.'s radar.

Joining HYDRA
"Be strong, sister. It won't be long before we have the power we need to fight."

- Pietro Maximoff When the twins reached adulthood, foreign powers began occupying Sokovia, driving the country into a state of turmoil. Pietro and Wanda took part in frequent riots to drive the foreign forces from their streets. What the twins did not realize was that the riots were orchestrated by HYDRA, who had taken up residence in the country and were using the riots to cover up their illegal experiments. The leader of the HYDRA forces in Sokovia, Wolfgang von Strucker, was attempting to harness the energy from the Scepter for a variety of uses, such as powering up weapons of mass destruction. List, desiring to see what effect the scepter's power would have on live humans, approached several Sokovian rioters, including Wanda and Pietro, offering them the opportunity to achieve the power needed to free their country from war. While Wanda expressed some doubt over Strucker's claims, Pietro was determined to free Sokovia and convinced his sister to accept.

While the other volunteers did not survive the scepter's power, Pietro and Wanda experienced drastic changes. The scepter unlocked latent supernatural powers within the pair; while Wanda developed a number of mental powers such as telekinesis, hypnosis, and energy projection, Pietro was now able to move at superhuman speed. Soon after, the Avengers arrived in Sokovia and raided the HYDRA Research Base, stealing the scepter and arresting Strucker. In the confusion, Wanda and Pietro escaped from their holding cells and, though inexperienced, were able to use their powers to evade the Avengers and escape. Pietro 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 was destroyed by the Hulk soon after.

A Misguided Partnership
"Yeah, you better run."

- Hawkeye to Pietro after he saves Wanda

Wanda and Pietro were soon called by Ultron to join him in his plans to destroy the Avengers, knowing that with their powers, they could tear the opposition apart. Soon after, Wanda and Pietro accompanied Ultron in acquiring Ulysses Klaue's supply of vibranium. When the Avengers arrived, Pietro attacked Captain America, then Thor, trying unsuccessfully to use Mjølnir against him. When Wanda attempted to "hex" Hawkeye, but was subdued by him, Pietro saved her in the nick of time. He took her outside Klaue's base, where she caught sight of the Hulk and managed 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. Wanda managed to stop it when it went off the rails, while Pietro used his super speed to save people on the road of the train. The Twins then accompanied Captain America back to Avengers Tower and tried to stop Tony Stark and Banner from bringing Vision to life. Pietro succeeded to cut off the electricity from Vision's cradle, but he was soon attacked by Hawkeye, only to witness Thor bringing Vision to life. After Vision proved himself an ally to the Avengers, he and Wanda then joined the Avengers in stopping Ultron and saving Sokovia.

Battle of Sokovia
To be added

Self-Sacrifice
"You didn't... see that... coming?"

- Pietro's last words to Hawkeye

During the Battle of Sokovia, Ultron hijacked the Avengers' Quinjet and began to fire its guns at civilians. Pietro bravely used his powers to save countless lives. When Ultron targeted Hawkeye and a civilian boy, he used his own body to shield them from the Quinjet's bullets, proving he was a true hero and a true Avenger. Unfortunately, Pietro died from his wounds, much to his sister's sorrow.

In honor of his sacrifice Hawkeye and his family decided to name their newest son Nathaniel Pietro Barton.

Powers and Abilities
"He's got increased metabolism and improved homeostasis."

- Maria Hill

Powers

 * Superhuman Speed: Quicksilver had the ability to run at extremely high, supersonic speeds. When imprisoned by Wolfgang von Strucker, he was able move from one end of his cell to another in less than a fraction of a second. His abilities made him nigh unbeatable in battle; in his confrontation with the Avengers, he managed to avoid multiple attacks, and knocked out Captain America in seconds. It was only his ignorance towards Mjølnir that allowed him to be caught off guard, knocking him out for awhile. Even then, he took down Captain America again and saved Wanda from Hawkeye.
 * Improved Thermal Homeostasis: Quicksilver could resist the side effects of moving at these speeds such as friction, reduced oxygen and kinetic impact.
 * Increased Metabolism: Quicksilver has a hyper-accelerated metabolic rate.
 * Superhuman Reflexes: Quicksilver's increased speed also augmented his reaction time, 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. As a result, Quicksilver tends to see the world around him as if it were in slow motion.

Abilities

 * Multilingualism: Pietro was fluent in Sokovian and English (albeit with a heavy Sokovian accent).

Family

 * Father †
 * Mother †
 * Wanda Maximoff - Twin Sister

Allies

 * Avengers - Enemies turned Teammates
 * Steve Rogers/Captain America - Leader
 * Tony Stark/Iron Man
 * Bruce Banner/Hulk
 * Thor
 * Natasha Romanoff/Black Widow
 * Clint Barton/Hawkeye
 * Nick Fury
 * Maria Hill
 * Vision

Enemies

 * Ultron † - Ally turned Enemy and Killer
 * Ultron Sentries †
 * HYDRA
 * Wolfgang von Strucker †
 * Doctor List †

Appearances
In chronological order:
 * Avengers: Age of Ultron Prelude - This Scepter'd Isle
 * Captain America: The Winter Soldier
 * Agents of S.H.I.E.L.D.
 * Season Two
 * The Dirty Half Dozen (mentioned)
 * Avengers: Age of Ultron

Trivia

 * In the comics, Quicksilver is a mutant and a founding member of the Brotherhood of Mutants, being initially identified as the son of Magneto (Erik Lehnsherr) and his then-wife Magda Lehnsherr (née Eisenhardt) in Vision and the Scarlet Witch #4 (1983), 19 years after Scarlet Witch and Quicksilver's first appearance. Magda leaves Erik while pregnant and takes sanctuary at Mount Wundagore in Transia, the home of the High Evolutionary, where she gives birth and later dies. The High Evolutionary then places them instead in the care of the Romani couple, Django and Marya Maximoff, who raise them as their own children. Prior to that, in Giant-Size Avengers #1 (1974), they were revealed to be the biological children of Golden Age superheroes The Whizzer and Miss America, a fact that was later retconned. In Avengers &amp; X-Men: AXIS #7 (2014), it was revealed that Pietro and his sister have no blood ties to Magneto and are not related after all. In Uncanny Avengers #4 (2015), it is confirmed not only they are not related to Magneto but they are not even mutants, as the High Evolutionary genetically altered them as infants, giving them their powers, before returning them to their true parents, the Maximoffs.
 * In the film, Pietro, alongside his sister Wanda, are not referred to as their comic book codenames.
 * The credits did in fact credit him as "Pietro Maximoff/Quicksilver".

Behind the Scenes

 * Another version of Quicksilver appeared in 's production X-Men: Days of Future Past and will return in X-Men: Apocalypse. He is portrayed by Aaron Taylor-Johnson's Kick-Ass co-star Evan Peters. That version is known as "Peter Maximoff", instead of "Pietro".
 * Aaron Taylor-Johnson was uncredited for his appearance in Captain America: The Winter Soldier.
 * Both Quicksilver and Scarlet Witch were originally going to appear in the post-credits scene for Guardians of the Galaxy.
 * An alternate ending scene was shot for Age of Ultron, featuring Quicksilver alive, joining the Avengers and wearing a new costume, along with his sister.