Brainchild

From publisher blurb: When Bethany discovered that her cousin was actually the glamorous super heroine AVATAR, she became her biggest fan. She also began trying to discover if her genetic relation to AVATAR meant that she, too, could conjure up the perfect version of herself... to no avail. Her disappointment turned into resentment and jealousy. She began scheming to make AVATAR look bad. She made plan after plan to show the world that AVATAR didn't empower women, at all. Her strong emotions eventually triggered the mutation she originally failed to awaken. Now, in her own "perfect" body, BRAINCHILD uses her powers to not only take AVATAR down a peg or two, but to lash out at all superficial people who made life for people like her so unbearable!