Not much is known about Ms. Maximoff's early life, other than she met Magneto and they conceived a child together. However, for unknown reasons, Magneto left her before Quicksilver was born. She told him she once knew a mutant who could control metal, but apparently didn't tell Peter that mutant was his father.
Ms. Maximoff greeted Charles Xavier, Logan and Hank McCoy on her doorstep, and believing them to be cops she asked them what her son Peter had done this time. While helping to break Magneto out of the Pentagon, Peter inquired about his ability to control metal, commenting that his mother once knew a man who could do it. Ms. Maximoff later watched the news with her children and saw a report showing Magneto's attack on the White House, reacting with horror and recognition when she saw him.
Around some point after the events from the White House, Peter figured out that Magneto was his father, having been unable to process the knowledge in such the short period of time he met Wolverine, Professor X, and Beast. He eventually figured it out and discovered Magneto's whereabouts after seeing him on the news and decided to go after him. Ms. Maximoff figured out what her son was planning and, knowing she couldn't stop her son, she advised him against it because she believes nothing ends well with Magneto.
- In the comic books, Quicksilver and Scarlet Witch's mother was a Polish gypsy named Magda, which happens to be the name of Magneto's second wife in X-Men: Apocalypse.