This reminds her of the inspiration behind the name. Wendy was standing in an elevator at the hospital. Her great grandmother had a stroke, and the family was on their way to be with her while life support was removed.
The elevator had two mirrors on either side of her. These parallel looking glasses were creating an image of eternity. The image was a repetition of both sides of Wendy. Standing there as a child experiencing death for the first time, Wendy realized there were two sides of life.
The good and bad sides show themselves continually into infinity. Growing larger or shrinking depending on perspective, these sides fluctuate like a pattern destined to repeat itself. And just like that, Wendy’s back in her head.