- Super-Speed. Google it.
- -- Quicksilver
Pietro Maximoff was kidnapped from Serbia and brought to Wundagore Mountain, base of the High Evolutionary, he and his twin sister, Wanda, were the children of Romany couple, Django and Marya Maximoff. The High Evolutionary supposedly abducted the twins when they were babies and experimented on them, once he was disgusted with the results, he returned them to Wundagore, disguised as regular mutants.
As adolescents, Wanda and Pietro discovered that they had unusual superhuman abilities. When Django began to steal food to feed his starving family, enraged villagers attacked the Romani camp. Using his phenomenal speed, Pietro fled from the camp with his sister. The circumstances of their separation from their family were so traumatic that not until well into adulthood could they remembered anything but the barest details of their childhood. For the next few years Wanda and Pietro wandered central Europe, living off the land.
Brotherhood of Evil Mutants
One day, Wanda accidentally caused a house to burst into flame through her hex powers, which she could not yet control. Superstitious townspeople began chasing her, thinking she was a witch. Despite Pietro's attempt to defend her, they were soon overpowered and were about to become victims of mob violence when Magneto came to their rescue. Magneto pressed them into service in his Brotherhood of Evil Mutants, costumed them, and named them the Scarlet Witch and Quicksilver. For months they served Magneto out of a sense of obligation and fear of his reprisal. As members of the Brotherhood, Quicksilver and the Scarlet Witch aided Magneto in his terrorist campaigns against humanity and helped him combat the original members of the X-Men.
When Magneto was defeated by the overwhelming powers of the alien Stranger, Quicksilver and the Scarlet Witch quit the Brotherhood; the Stranger transported Magneto away from Earth, and the Maximoff twins returned to Transia.
Joining the Avengers
Pietro and Wanda sought refuge with the Avengers, a world-renowned team of super heroes. They were inducted along with Hawkeye to take the place of the charter members, who wished to take a leave of absence. This foursome was nicknamed "Cap's Kooky Quartet". At first it was looked upon as less capable than the previous roster, but defeating Kang the Conqueror, Doctor Doom, and other threats quickly proved their worth. Although the hot-tempered Quicksilver and Hawkeye often both rebelled against his orders, Avengers leader Captain America molded them into valuable team members.
Humanity's suspicion of mutants still rankled Quicksilver, and he briefly rejoined Magneto after the latter returned to Earth, compelling his sister to come with him. The X-Men and Avengers eventually defeated Magneto.
The Scarlet Witch then began a quest to recover her powers by studying grimoires, with Quicksilver and the Toad supporting her. Her studies accidentally summoned extra-dimensional caudillo Arkon, who kidnapped the Witch to made her his bride, the Toad when he opposed, and then a number of Earth-born scientists in an attempt to use atomic power to save his own world Polemachus even by destroying Earth. Quicksilver gained the help of the Avengers to save his sister, the Avengers managed to save Polemachus without damaging Earth, Arkon ceased any further violence against Earth and renounced to the Scarlet Witch, and Quicksilver and the Scarlet Witch eventually resumed their membership with the Avengers. The Toad chose to remain at Polemachus.
Seriously injured during the Avengers' battle against the Sentinels, Quicksilver was taken to medical care by Crystal, a member of the royal family of the hidden race of Inhumans. Months passed before Quicksilver was well enough to contact his companions to tell them what had happened to him. During that time Quicksilver became romantically involved with Crystal, and the two married after a brief courtship. The Inhumans, the Avengers, and the Fantastic Four attended the wedding, held in the Inhumans' refuge of Attilan, then located in the Himalayan Mountains.
Not long after the birth of his and Crystal's first child, Luna, Quicksilver learned the alleged truth about his parentage. Magneto had stumbled upon Bova and learned from her that Wanda and Pietro were supposedly his children.
Confronting Quicksilver and his sister in Attilan with this revelation, Magneto apparently hoped to sway his children to rejoin his crusade against humanity. But Quicksilver denounced Magneto for his callous treatment of them when they were members of his Brotherhood, and refused to believe he had changed his ways.
A man of action, Quicksilver volunteered his services to the head of the Inhumans' small militia and became an officer. During the period of his service, however, the Inhumans had no call for military activity.
Quicksilver's neglect of his wife led Crystal to become involved with another man. Learning of her infidelity, Quicksilver refused to forgive her and fled Attilan, vowing vengeance on her and all those he perceived as having wronged him. Unknown to anyone, however, Crystal's malevolent cousin Maximus was manipulating Quicksilver's mind, fanning Quicksilver's anger at Crystal into a rage directed against his former colleagues in the Avengers. Quicksilver framed the Avengers for treason, thereby turning the federal government against them until they cleared their names. Quicksilver also led the members of the android version of the criminal organization Zodiac against the Avengers, fought the Fantastic Four, and joined forces with various Soviet-era Communist operatives against the Avengers' West Coastdivision.
Eventually Maximus' control over Quicksilver's mind lapsed and Pietro ended his criminal ways. The Inhumans' monarch Black Bolt commanded that the reluctant Quicksilver reconcile with Crystal. Their initial attempts failed. Quicksilver unofficially joined the Avengers' West Coast branch for a time. Eventually Crystal took Luna to Earth and joined the Avengers, and Quicksilver shortly afterwards became a special operative of the United States government as part of its new, Havok-led version of X-Factor.
Quicksilver and Crystal again attempted a reconciliation, but Crystal was romantically involved with the Black Knight. They reconciled after the Black Knight left Earth-616, seemingly permanently. Quicksilver left X-Factor and again became affiliated with his wife's team, the Avengers. However, their happiness was short-lived, because Crystal seemingly perished in the Avengers' battle against Onslaught. In actuality she, along with many other members of the Avengers, had been transported to an alternate reality. During her absence, the High Evolutionary asked Quicksilver to become the leader of a small band of his Knights of Wundagore, animals that the geneticist had endowed with human intelligence and humanoid forms. Quicksilver accepted and for a time led the Knights in battles against injustice. Quicksilver and Crystal were happily reunited after she and the other missing Avengers finally returned to their native Earth. They split, however, when she could not choose between Quicksilver and a returned Black Knight.
House of M and Decimation
When his sister lost her sanity and her control over her ever increasing power, she killed several Avengers, leading to their disbandment. She was taken into the custody of Magneto, who asked Professor X to try and help her. Xavier's treatments weren't successful however, and as Wanda's condition worsened, the Avengers and X-Men met to discuss what to do with her. Quicksilver found out about the meeting and that they were discussing euthanising Wanda. He told his father, but Magneto, at the end of his rope, believed that they might be right to do so.
In order to save his sister, Quicksilver convinced her to use her powers in tandem with Xavier's telepathy to warp reality and create a new world, where they would all have what they wanted. Wanda did so, and created a world ruled by Magneto where mutants were a thriving majority and Quicksilver and Wanda were royalty. However, this new reality began to crumble when several heroes began to remember the old world due to the powers of Layla Miller. Believing Magneto to be responsible, they attacked him and his family in Genosha. There, Layla Miller restored his memory as well, and the heroes realised that Quicksilver had been the one to manipulate Wanda into warping reality. Angry over what his son had done in his name, Magneto lashed out and killed Pietro. This finally drove Wanda over the edge. Angry that their father had always put mutantkind before his children, Wanda restored reality again, only now without mutants.
Some mutants were saved by Doctor Strange and Emma Frost, retaining their powers. Quicksilver was one of the mutants who lost their powers. As a result of losing his powers, his sister, and his reputation, Quicksilver fell into a deep depression.
When an angry Spider-Man confronted Quicksilver for his role in creating the House of M reality, of which Spider-Man still maintained memories, Quicksilver jumped off a roof in an attempt to commit suicide, seriously injuring himself and possibly breaking his spine. Crystal, whom Quicksilver had tried to contact earlier, teleported in to find her ex-husband. Crystal teleported him to the Inhumans for medical attention, believing he had become suicidal upon the loss of his powers and unaware of his true connection to the events.
After treatment by an Inhuman healer, Quicksilver woke up and was reunited with his daughter Luna. Deciding that he could not stand life as a human, Pietro asked Black Bolt for permission to undergo Terrigenesis. Quicksilver's request was denied since he was of human stock, and Terrigenesis was reserved only for pure Inhumans in order to decrease the chance of detrimental mutation.
The Terrigen Mists
Luna introduced Quicksilver to a "communicator" who told Pietro much about the process of Terrigenesis, leading to Quicksilver breaking into the sacred Terrigen Caves and knocking out a guard so he could dive into the misty waters inside. Quicksilver returned to his room, thinking that the exposure had no effect on him, only to be greeted by an older looking Quicksilver.
The older Quicksilver explained the nature of his new powers, the ability to time travel, and of the plan that came to pass. Quicksilver began working with his older selves to realise a plan to take the Terrigen Crystals back to Earth and restore the mutant population his sister had decimated. He set about gaining Luna's loyalties, and promised to bring her to Earth with him. Eventually, Quicksilver managed to get a container full of Terrigen Crystals to the past, and used Lockjaw to take him and Luna back to his apartment in New York.
Luna instructed Lockjaw not to let Crystal find them before he headed back to the Inhumans. Quicksilver explained the basis of his plan concerning the Terrigen Crystals, and told her he was going to give her birthright and exposed her to the Terrigen Mist, giving her the ability to "see" and manipulate "souls" and emotions. After gaining some funds by jumping to the future and using winning lottery numbers, he then traveled to Genosha and convinced Callisto to sample some of the Terrigen Mist herself, which promptly restored her heightened senses to the ultimate degree. Quicksilver told Callisto to gather up the remaining depowered mutants so that he could restore their powers. Callisto went to find other depowered mutants, and it began to rain, which caused her intense pain, as she realised that Pietro's attempt to restore her powers had caused them to go out of control, making her senses too heightened. Magneto came across her, and learned that his son was behind her suffering.
Nevertheless Quicksilver continued his "mission", re-powering the rest of Genosha's mutants. Confronted by Magneto, who verbally assaulted him and discredited Pietro by showing the other mutants what had happened to Callisto. In retaliation Quicksilver used his new-found power to pummel Magneto with the aid of two "temporal dupes", and only the sight of his crying daughter stopped him from killing his own father, whom he hated for never acknowledging or loving him.
After a brief encounter with the Inhumans, U.S. government agents shot Quicksilver with a tranquilizer dart in an attempt to immobilize him. What they really sought, however, was the tank of Terrigen Mist. In an attempt to save his daughter, Pietro ordered Lockjaw to teleport her away from Genosha. This proved a fortuitous move. Despite a warning by the Inhumans to return the tank, the agents attempted to escape with their newly acquired cargo. Left to deal with the situation on his own, Black Bolt whispered the word "war," preventing the agents from escaping and causing massive destruction to the surrounding area. As a result, this action was taken as a sign of open conflict between the Inhumans and the U.S. government. After escaping from the battle on Genosha, Quicksilver bathed himself in the Terrigen Mists for what seemed to be weeks on end, going so far as to absorb the crystals into his own body. He used the Terrigen Crystals to travel farther into the future than ever before, and upon his return spoke of a monstrous disaster yet to come. Having gained the power to restore the super-human abilities of former mutants, Pietro "cured" a man on the street that turned out to be the villain known as Reaper. As he walked away, Quicksilver appeared more mentally unstable than ever before as he chose to accept the destruction that lay ahead.
He ran afoul of some of his former X-Factor teammates, as he set up shop in Mutanttown, offering his services in curing former mutants. When X-Factor confronted him about his methods leading to several former mutants dying or being injured, Pietro simply dismissed them as having been deemed not worthy. After attempting to convince X-Factor member and former mutant Rictor to accept his help, Rictor used his temporarily restored powers to exorcise the crystals from Pietro, to stop him from harming anyone else. Pietro continued his descent into madness, attempting to kill Layla Miller for being a vessel of the devil. He failed, and was arrested for vagrancy.
Divorce, Re-powered, and the Mighty Avengers
While in jail, Quicksilver experienced a series of hallucinations, of his sister Wanda, his ex-wife and daughter, and his father. One of the hallucinations told him that the Terrigen crystals had run their course in his body, and after snapping out of his hallucinations, he found that his powers had been restored. Escaping jail, Quicksilver rescued an innocent and rediscovered his desire to be a hero.
After these events, Pietro obtained a new costume and rejoined the Knights of Wundagore serving as a scout and gathering intelligence but was later captured by Modred. The sorcerer transferred his consciousness into Chthon's spell book while transferring Chthon's consciousness into Pietro's body. Hank Pym and his new Mighty Avengers eventually thwarted Chthon and Pietro was returned to his body with the help of the new Vision (Jonas). He initially declined Avengers' membership offered by Hank Pym (now the Wasp), but he changed his mind after seeing his sister, the Scarlet Witch in their ranks.
Unbeknownst to him and most of the Mighty Avengers, it was really a disguised Loki. Pietro chased after the Mighty Avengers hoping to catch them and reinstate their offer, but Hank declined because of his former teammate's initial response. Wanting to prove himself, the speedster continued to chase the group's activities persistently aiding them on multiple missions in which Pym and the Avengers gratefully accepted him. Pietro participated in all of the team's missions hoping to speak with his sibling but met with no success. After opposing the powerful Inhuman known as "the Unspoken" Pietro recovered the remaining Terrigenesis crystals returning them to the Inhumans and clearing his name of criminal charges through a lie that a Skrull committed all of his felonies during the Secret Invasion events. While the Wasp (Pym) and Jarvis know the truth behind his deception, both have kept it secret and want him to continue on his road to redemption. Their views however, are not shared by Pietro's daughter Luna; while she keeps the truth secret out of love for her father, she will never forgive him for his past actions and may never see him as the man he is trying to revive.
Quicksilver finally learned that the person he thought was his sister was actually Loki in disguise. Enraged, he and the rest of the team traveled to the Isle of Silence to set a trap for the god of mischief. After imprisoning Loki in a device designed by Hank Pym, he began torturing the god for information about Wanda's whereabouts. Loki offered no information about her and managed to contact Thor to beg for his help. Thor arrived and attacked Quicksilver for the way he was treating Loki. He was able to outrun the thunder god's lightning but was eventually overpowered. He was one of the Avengers who joined Hercules, Amadeus Cho and their allies in an assault on Olympus Group Headquarters. He battled Amazon warrior women alongside Zeus and helped a wounded Wolverine defeat the Huntsman, stabbing him through the chest with his own weapon.
Quicksilver was later summoned by the Ghost using Amadeus Cho's technology, to defend Asgard against the Thunderbolts. He single-handedly defeated Mister X who was in possession of the Spear of Odin. Mr. X wasn't able to react quickly enough despite his abilities and Quicksilver viciously beat him down with a piece of debris. He was alongside the other Avengers against the Void-possessed Sentry in the events of Siege.
Pietro joined the Avengers Academy as staff. His first act as a teacher was to get Jocasta to rebuild an Arsenal robot and use it as a test against the students. He was then blackmailed by one of his students, Finesse who deduced that Pietro was lying about being replaced by a Skrull, into teaching him the same methods and strategies that Magneto taught him in the Brotherhood of Evil Mutants.  Pietro developed a closer student-teacher relationship with her, especially after Magneto payed a visit to the school and Finesse asks Pietro to teach her to be like him instead of like Magneto.
Avengers vs X-Men
Quicksilver sided with the Avengers against the X-Men. After he failed to convince his sister to join him on the side of the Avengers, he alone attacked his father.
When his half-sister Polaris was getting drunk and demolishing a bar, Quicksilver intervened to try and stop her. After a short conversation, the two began fighting. Quicksilver managed to knock her out, but before he could apprehend her on behalf of the Avengers, she was taken into police custody.
Concerned about his sister, Pietro tracked her to Serval Industries headquarters, where she had accepted a job to lead the company's superhero team. Claiming that he had a falling out with the Avengers, he volunteered to join the team, and Polaris accepted, with Harrison Snow's, CEO of Serval, blessing.
Soon after the World War Hate, Quicksilver joined forces with Magneto to stop the Scarlet Witch, who had been affected by a spell gone wrong which turned her moral compass upside down, from murdering Doctor Doom. Wanda cast a spell to affect those with blood ties to her, and even though it affected Pietro, it didn't affect Magneto, revealing that they actually weren't Magnus' children.
With the help of the spirit of Doctor Voodoo's brother Daniel, Wanda was possessed so a reinversion spell could be cast, which successfully brought back to normal almost everybody affected by the inversion spell, including Wanda.
In the wake of the conflict, Quicksilver joined the Avengers Unity Division.
Wanda and Pietro returned to the Wundagore Mountain to find out their true parentage, and they were brought to the reformed Counter-Earth, which the High Evolutionary used to test and try to create his perfect New Men. The twins encountered the Low Evolutionary, the leader of a resistance formed by the High Evolutionary's rejects.
After being tracked down and defeated by Luminous, a new creation by the High Evolutionary with both Quicksilver's and Scarlet Witch's powers, Wanda and Pietro were brought to the High Evolutionary himself. He revealed them that Django and Marya Maximoff were their true parents, as well as the truth that the twins were supposedly not mutants but they had been experimented on by the High Evolutionary. After escaping from the Evolutionary's experimentations, Pietro and Wanda located the Avengers Unity Division, who had travelled to the Counter-Earth looking for the twins, and helped the inhabitants of Lowtown, a refuge for the High Evolutionary's rejects, from their creator's assault. After the High Evoltuionary was forced to flee through a portal once he was defeated, the Unity Division returned to Earth.