Dizzy is a manifestation of the powers that Hein, Lily, Rai and unbeknownst to her, Ligeia gained in the Dark Woods. He takes form of a red cat in the Fantendoverse where he can casually walk through the streets without being noticed. He can transform to his true form which is a gigantic, more humanoid, version of him. He towers over Hein and Ligeia and even Father Trip, one of the tallest characters in the series, but isn't as tall as Slender Man.
As a vessel for their powers Dizzy can transfer/lend the powers to them in the Fantendoverse by clutching his nails to them. However over time Hein and Ligeia get full control over their powers, rendering Dizzy almost useless, having only the powers of Lily and Rai in him. Near the end of the story Dizzy transfers all the powers of Lily and Rai into them as well, having been able to do that all along but wanted to spend more time on Earth with them. He then goes into the subconscious of Hein and lives on as a hollow remnant, being able to see all the things Hein does.