In the original Brothers Grimm she and her brother Hansel venture off into the woods and find a gingerbread house owned by an evil witch. Being fooled, they are trapped and used as slaves until the witch wants to eat them. Knowing this they kick the witch into an oven an burn her alive.
Gretel grew up with her brother Hansel in the Homelands, until their parents turned them out. They stumbled upon Frau Totenkinder's house made of candy, and when it became clear that she meant to eat them, they threw her in the oven and burned down her house. After their ordeal they left the woods to find the Emperor attacking. They found their way to the Mundane world and to Fabletown, where Hansel was horrified to find Frau Totenkinder alive and well. He refused to stay near her, and left to Europe to ignite the witch burnings of the 17th century. Gretel, however, stayed behind and began studying magic under Frau. When Hansel returned to discover this, he murdered her and told the other Fables it was an accident. They put her body down the Witching Well. When Flycatcher entered the Witching Well, Gretel's ghost was one of many he encountered and led back to the Homelands to help build his new kingdom.