Based on the movie, Joker. Pinky and Brain suffer from their own mental issues while living in the trashed town of Hamington. They are human in this. Brain is 49 and Pinky is 26.

A story about Pinky's origins. Pinky has an odd habit of pretending things are alive. Especially the spool he refers to as "Sis." What if it wasn't just a silly game in his head. What if, at one point, there WAS a Sis? Not just a sister, his twin sister, of course. Will Brain be able to piece together what's happening to is dearest friend? Eventual PxB.