What do you mean by "Inversion of the E"?
"E" being Enantiomorph, cause I was too lazy to type it all out again after I did two words before.
In a traditional enantiomorphic relationship, we have a King being cast out by a Rebel, who then becomes the King. We also have the "female principle" over which they are fighting, and the "shield thane" who stands witness to it all. It is a permanent state and an ever-repeating cycle.
The only criteria of the HoonDing is that he "perseveres over infidels." In Cyrus' case, this happened to be the King of Empire, but with Hunding as a HoonDing, it was instead the natives of Hammerfell who were driven out. Either way, it isn't a permanent state (Cyrus isn't the HoonDing when he defeats Vivec), and neither must it repeat (no one drives the HoonDing out of Hammerfell). The inversion (though I hesitate to call it such) comes from the fact that the Rebel and King combine to form the HoonDing, rather than supplanting and becoming eachother.