Percival Edward "Eddie" Chang, better known as Grunge, is a superhero and member of the team Gen¹³. Grunge has the ability to absorb the molecules of materials and utilize the properties of those materials to adapt his physiology. Grunge also has a brown belt in kempo, aikido, jujutsu, kung fu, and taekwondo.
Grunge met the Turtles at the beginning of Gen¹³ issue 13B. Buried under a mountain of their own merchandise, Grunge helps them out from their predicament. They indicated that the Frenzy Beast attacked them and left them worse for the wear. The Turtles point Grunge off to follow Frenzy Beast by his path of destruction.