Miranda's mutant ability first manifested when she was six years old, after she got into an accident. Her daughter, Emily, inherited Miranda's mutant power. She often used her power unknowingly, such as when she was feeling fearful or in danger, which affected her relationship with her family and friends. Eventually, she developed a better understanding and control over her power.
Miranda is also an important character in the graphic novel "Heroes: The Recruit".
Overall, Miranda Keys is a complex and compelling character who grapples with her powers, personal struggles, and the challenges of being a mother and a hero.