Twin siblings Pietro and Wanda Maximoff made their first appearance in X-Men #4 in March 1964, created by Stan Lee and Jack Kirby. Though they were raised by the gypsy couple, Django and Marya Maximoff, the twins are the children of Magneto, one of the most powerful mutants in Marvel Comics. Pietro, known as Quicksilver, possesses superhuman speed and Wanda, known as Scarlet Witch, can control probability.

During their teen years, life was difficult for their family leading their adoptive father to steal food to support his family. When angry villagers attack their gypsy camp Quicksilver uses his speed to flee with his sister. For the next few years the pair wander through Europe until Scarlet Witch is attacked by a mob when she accidentally lights a house on fire. Magneto saves them from the mob and recruits them to join his Brotherhood of Evil Mutants.

After several fights with the X-Men an extraterrestrial transports Magneto from Earth leading the twins to leave the Brotherhood. Quicksilver learns that the Avengers are seeking new members so he convinces his sister to go to America and join the team. They worked with Captain America and Hawkeye becoming the second generation Avengers, nicknamed “Cap’s Kooky Quartet.” Quicksilver believed that he should be the leader of the group but is captured by the Mole Man during their first mission and rescued by the other Avengers.

Then Scarlet Witch gets shot accidentally during a mission fighting Magneto. Once again Quicksilver takes his sister and flees the Avengers. Magneto manipulates them into joining him at his mid-Atlantic base where they fight the X-Men, with Quicksilver engaging in a spirited fight with Cyclops. During an appearance in The Amazing Spider-Man Quicksilver and Scarlet Witch realize that Magneto is a real villain. They are kidnapped along with other villains by robot Sentinels then freed by the X-Men.