S2·E15 Teresa -- The Beginnings of Love

Mark Venture flies down to the surface to meet Trelaina. She explains the danger of the Comet Empire and reveals her god-like power which had once destroyed all other life on her planet. She has sworn "never to use that power again to take anyone's life. Never again."

Mark begs Treleina to help Earth fight the Comet Empire. But she declares that she must stay behind with her planet even though the Comet Empire is on a collision course with it.