Quicksilver and his sister the Scarlet Witch have reluctantly joined Magneto's Brotherhood of Evil Mutants in his plans to rule the Earth when Wanda became in debt with the master of magnetism who saved her from the superstitious inhabitants of a small European village. Soon, the team takes over the small Republic of San Marco and submits its inhabitants using fear. Quicksilver uses his mutant speed to help defend Magneto's new castle against the X-Men. When the heroes are about to defeat them, Pietro is appalled by Magneto's decision to sacrifice the population of San Marco to destroy the X-Men with a large bomb so he quickly disarms the explosive before the Brotherhood escapes.
The Brotherhood of Evil Mutants once more engage in battle against the X-Men who force them to escape from their space station.
Thinking that he might be a mutant, Magneto tries to get Namor to join his Brotherhood of Evil Mutants but Quicksilver does not trust him. The X-Men attack them on Magneto's island and the Sea Prince decides not to ally himself with Magneto. The Evil Mutants are forced to escape.
Looking for a way to defeat the X-Men, Magneto finds the Blob in a circus but the carnies get into a fight with his Brotherhood of Evil Mutants. The Blob refuses to join Magneto until a concussion brings his memory of the X-Men back. During a fight against the X-Men, Quicksilver and the Scarlet Witch are appalled that Magneto was willing to sacrifice the new recruit to destroy his enemy, which causes the fat mutant to quit the team.
Magneto sends his Brotherhood on a search for the X-Men but when they find them, they realize that they no match and run away,
Pietro is transported to Arkon's dimension with the whole Avengers Mansion. There he gets captured along with Vision, Wanda and Clint. After being freed, Quicksilver and the Avengers defeat Arkon and Enchantress.
Pietro unknowingly lands on Earth-712 and has a vision of it being destroyed by the sun. After learning the possible reason for the cataclysm, he and his fellow stranded Avengers beat the Squadron Surpreme and fly off to stop the catastrophe.
Growing tired of Magneto's evil, Pietro wants to run away with his sister, but they finally decide to ask advice from the Fantastic Four at the Baxter Building. Due to their reputation, the Human Torch and the Thing welcome them as criminals and the encounter turns into a fight. Realizing that going there was a mistake, the two mutants return to Magneto.
Pietro listens as T'Challa tells of his origin.
He is present at the Avengers-Meeting.
During a battle against the X-Men who interfered in Magneto's plan to recruit the Stranger, Quicksilver is frozen by Iceman. After Cyclops unfreezes him, Quicksilver agrees with his sister's decision to never serve Magneto again. They are offered to join the X-Men but they prefer to stay out of conflicts and go back home in Central Europe.
Learning in the papers that the Avengers are recruiting members, Quicksilver convinces his sister that they should apply since being an Avenger won't be a constant reminder that they are mutants. Once in America, they are greeted by Tony Stark and accepted as new members of the Avengers.
The new members of the Avengers get a visit from Thor, but their first encounter is not very cordial.
As the Avengers are searching for the Hulk to add muscle to their team, they fall into a trap set by the Mole Man and find themselves in the pit of the Minotaur. Separated from his team by a subterranean rockslide, Quicksilver is gassed and captured by the Mole Man's slaves. After defeating the Minotaur, his teammates come to his rescue. The Mole Man then decides to send them back to the surface before they destroy him too.
The Avengers travel to Sin-Cong to free its people of their Red tyrant, the Commissar, who turns out to be a robot controlled by the Communist army.
While Quicksilver attends Reed Richards and Sue Storm's wedding at Baxter Building, he realizes that the Fantastic Four are attacked by several of their old foes so he decides to lend a hand. Racing after the Human Top, Quicksilver easily knocks him down. While the battle rages on, Reed Richards uses a machine that transports all their enemies back to the recent past with no memory of what occurred. Finally, Reed and Sue are wed in front of all their family and friends.
After hearing Cap's tale of the Greymoor Castle, Wanda wonders if he got trouble for deserting his platoon. Cap tells his friends that high ranking officers knew about his secret identity and made up a cover story for his absence.
Quicksilver and the Scarlet Witch take down the Swordsman who has intruded the Avengers Mansion pretending he wants to join their team. After he escapes, the Swordsman, who carries quite a bad reputation internationally, uses Captain America's interest in being part of Nick Fury's team to lure him into a trap. His teammate track him town to a warehouse where the villain threatens to push their capture friend down a building if they don't make him leader of the Avengers. But Cap jumps off before they agree. With teamwork, they manage to save him. Then while they fight the Swordsman, their foe suddenly vanishes. Back at their headquarters, Hawkeye and Quicksilver once more question Cap's leadership, but finally come to a truce. Then they get a message from Iron Man saying that he vouches for the Swordsman's membership so they decide to take his word and give the man a chance. Some time later, Cap and Hawkeye catch the Swordsman apparently setting a bomb, but the villain escapes with the bomb which detonates outside their HQ,
The Avengers experience some weird events where their interventions are perceived by the press as criminal. With more and more incidents involving them, the authorities force the Avengers to disband, and due to their already conflictive relationship, they part in bad terms. Pietro tries to find a job in a carnival act, but due to the recent bad press, the only man to open the door is the Ring Master who welcomes them among his carnies. But the hypnotist's attempt to convince them to pillage the audience fails so the former Avengers engage combat and defeat the Masters of Menace. The Ring Master calls the police, forcing his troublesome recruits to flee. Thanks to Captain America' trick to get Power Man confession on tape and after Princess Python has admitted the truth to the D.A., the authorities reinstate the Avengers' status and even decide that an official Avengers Day will be held. But later, Captain America tells his teammates that he's quitting anyway.
After Captain America's departure, Kang captures the remaining Avengers and takes them to his own century. Thanks to his sister, Quicksilver manages to escape his containment and, coming face to face with Captain America who has found a way to track them down, he realizes that his missed his partner. As the team reunite, they realize that Kang intends to overthrow the current king and marry Princess Ravonna. The Avengers choose to side with the people. They convince the king's army to fight back, but Kang manages to take over anyway. Kang's refusal to slay the conquered princess provokes a rebellion amongst his commanders and the conqueror gets the help of the Avengers to stop the war and save the princess in exchange for their safe return to their century.
Getting a letter from an aunt in Latveria, Wanda and Pietro are thrilled at the idea of finally meeting someone in the family who can tell them about their parents. The other Avengers decide to accompany them, but it's all just a trap set by Doctor Doom who seals the land within a giant dome right after their arrival. Their joint effort enables the heroes to lift the dome away and escape.
