SOLVED. Childrens fiction, maybe YA. A boy who is mistreated has to save a parallel world from destruction.

[Abdi]

I read this book back in middle school, that was in the late 2000s, early 2010s. It was a series of books but I only read the first one. It was about a boy who is mistreated and is called an idiot, and he has to save a parallel world. A monster or a beast of some kind is sent to help him find a doorway into the parallel world. The beast had to fight another monster to stop it from killing the boy. When the boy goes into the parallel world, it is described in a weird and funny manner. The book was illustrated.

[Abdi]

I found the series, its called, Leven Thumps and the gateway to Foo.

[Rainbowheart]

Glad you found it!

Leven Thumps and the Gateway to Foo for the link.