Ben's insecurities over the Omnitrix are aroused when Xylene, an alien friend from Grandpa Max's plumber days, suddenly appears. Unable to accept not being the center of attention (after all, how could anyone not admire and covet his acquired powers?), Ben despises her presence. In due course he learns an embarrassing truth about the Omnitrix - it was indeed meant for a Tennyson to possess, but not Ben. Meanwhile, a Vilgax robot reawakens to carry out its mission, making Ben the center of its attention.
—statmanjeff