"Who's next for my mercy?"Undyne is one of the main characters in Swapfell, and the opposite of Undyne in Underswap. She takes the Royal Scientist role in Swapfell.
AppearanceShe is often depicted with glasses and wearing a lab coat, covered in blood, with a black holster holding test tubes like a pocket against her chest. Her hair is tied in an updo, and she's sometimes shown with her fins ripped and several wounds. She is sometimes seen using a chainsaw or huge scissors.
Like the other Swapfell characters, Undyne is evil, and slightly psychotic if her personality is anything like Underfell Alphys'.
Some think Undyne uses Alphys as a test subject.
She's known to be both smart and strong, but her true abilities are unknown.