Before she became the unlikely heroine, Alexandra was never "quite" normal to begin with. Born without a fully functional immune system, it was feared that she would have to live out the course of her natural life in a hermetically-sealed bubble.
However, when a team of biologists attempted to remedy her situation using a recently-discovered element from the cosmos things went haywire, causing a massive explosion what nearly wiped out the entire laboratory. Of the survivors, only Alexandra and the lead scientist made it with their lives. However, Alexandra had begun to exhibit strange features never seen in the average human being, not to mention the ability to resist disease and sickness had been finally achieved. In fact, her entire body's defensive mechanisms were boosted, granting immunity to poisons and enhanced superhuman durability. In addition, she has somewhat enhanced combat capability and is able to augment her strength by generating energy or expelling it in pulse blasts.
One night when a bad storm strikes the area, the laboratory loses power, allowing her to escape containment, but she wasn't the only one...