Crossed with Nightmare Fuel. The life of the Imaginary Friend World, he's probably the biggest woobie ever. First he was separated from his creator by the kid's own parents, then he spent god knows how long alone in a trunk driven nearly insane. Then he meets Frankie (someone in a rather similar situation to his own, or at least he thinks so...) Then the others try to take Frankie from him and his imaginary world, so naturally has an emotional breakdown that literally breaks his entire world apart.
World: She has to stay! Without her my world is empty, and I'm nothing!
World's Freak Out when he and Frankie play Hide and Go Seek.
Frankie: It's called Hide and Go Seek, not Hide and Freak Out.
World: (hugs Frankie and babbles unintelligibly while crying)