[@Jbcool] Yea, [@BCTheEntity] basically called it. The idea is that he genuinely believes Khorne and Tzeentch are actually Gork and Mork. The only point of difference is that no one is entirely certain which god(s) he's actually serving the will of at any given point in time, let alone in general.
Though originally gifted by Gork and Mork, he used his powers to dabble in the dark arts of the spiky 'umies, making deals with many a daemon and chaos entity along the way. His wicked ways come to a head after he's captured by sky 'umies wearing blue and gold armor what don't talk. Once aboard their flyin' boat, he escapes 'iz guard and flees to his clan. Apparently, 'iz name 'ad gotten passed around by the daemons he liked to summon, and some git named Air-man was lookin' for 'im. Things don't go according to plan, 'e steals a book written by some red git, then gives it to some crazy panzees that want it for der boss's collection so they'll rescue him. While he's away, havoc befalls his clan as a result of his debt to the daemons, and when he tries to return they cast him out, forcing him to accept the panzees' offer to take him somewhere he'll be safe.
When all is said and done, no one involved is entirely sure if he's an agent of the ork gods, the chaos gods, cegorach, or maybe even Mephet'ran. That said, in his mind, he is adamant that he is a servant of the Great Green Gods.

All subject to necessary scrutiny and change, of course.