It looks like he’s smoking a blunt. Like that Koffing ate a pound of marijuana and is leaking out pot fumes everywhere and Petrel is just high as fuck rolling around on the floor.
A drawing I commissioned from Rubyconcream. I like to believe that whenever Petrel wants to go somewhere, instead of taking a car or whatever, he just ties strings to all of his Koffings and floats around like Mary Poppins.