The Switchind Sides Sandworm begins the story on the side of the villain but ends it on the hero's side. Why? Love.

Maybe she and the hero are both stuck on a spaceship at the other end of the galaxy and she discovers his kindness and her newfound feelings for him. Or maybe she finds out that she's been lied to by the villain all her life and has been working for the very people she thought she was fighting against while the hero has been honest with her and is the one she wants to be with. Somehow, she falls for him and decides to defect to his side.

The Switching Sides Sandworm will most likely never be evil, only misguided or manipulated. Since she is essentially an ordinary citizen of The Empire, she sometimes also serves to humanize their average citizen. While almost Always Female, males can just as easily fulfill the same role.

Most of the time, unlike the Mad Scientist's Beautiful Daughter, the Switching Sides Sandworm is the primary female lead, quite capable of taking care of herself, and her Character Development is a major part of the story. It's a good thing, too — she tends to have a few sources of angst in her past that require a lot of dealing with before she and her man can ride off into the sunset together.

If she doesn't switch sides, it's Dating Catwoman. While a High Heel Face Turn may be done for a number of reasons, this trope's defining trait is love.