Heather's world was changed permanently when the X-Men tracked her down in her home in Surfer's Paradise, Australia. She and her brother were revelaed to be the biological children of a local crimelord who had just been murdered, and the X-Men came to keep rival gangs from killing his children. Lifeguard's powers were quickly discovered by the X-Men when Heather saved her brother and Storm from drowning. Later, in a fight with the rival gangs, she manifested a golden armored skin to fend off bullets, which became her "default" power-up. Lifeguard joined the X-Men in the fight against Lady Mastermind and Sebastian Shaw, who were angling to take over the Australian underworld. Her powers allowed her to manifest enough telepathy to enter Sage's mind and help free her from Lady Mastermind's brainwashing, though Sage had to commandeer her mind to fully free herself. This drove a wedge between the two women, which was exacerbated when Sage later jumpstarted Davis Cameron's powers in order to find Heather after she was kidnapped.

The variety of Lifeguard's power manifestations appear to be almost limitless. She has grown wings for flight, extra arms for carrying and super-strength. She can also manage more that one power at a time. During the alien invasion led by Khan, however, Lifeguard's powers began to inexplicably transform her into a bird-like humanoid, which was recognized by the invaders as the form of a Shi'ar Royal. This led her teammates to believe that Heather's mother may have been a Shi'ar.

Unfortunately for Heather, her brother Davis refused to accept her changes and even went so far as to claim that she was really an alien who had replaced his sister. Davis disappeared after expressing his disdain for Heather, and left a note asking her not to follow him. Heather refused to listen, however, and left the X-Men with Thunderbird III to find her brother.