A water spirit finds a rainbow wig
 
I’ve decided that this goop is actually its own character named Glass, as opposed to simply being a goo version of each character. “Glass” refers specifically to her eye, which doubles as her core. She constantly secretes a thick, goopy substance magically connected to her being, which (as a side effect) takes on a messy representation of whoever she’s around as she senses and takes in their magical signature. She can’t talk and rarely communicates beyond head gestures.