Balthaas Direnni 2E, 597
I have a most intriguing theory on both the natures of Sheogorath and Hermaeus Mora and that these two are inextricably linked, these are both the Daedric princes of madness Sheogorath is the prince of amnesia, new creation. while Hermaeus Mora a prince of memory, old creation. In this sense we can see that Mora is a far more Anuic entity than Sheogorath and that they almost form the extremes of Anuic and Padomaic mentalities, Similar to Mehrunes and Baal.
The most intriguing parts of both princes is that they hold significant dominion over the mortal world, more than any other princes. Over the city of Vivec is a giant meteor, Baar Dau, this meteor was supposedly sent by Sheogorath on a whim, this is strange, usually even during the Planemeld, Daedric princes require cultists, mortal servants already on Nirn, in order to manifest or intervene. this is not true for either Hermaeus Mora or Sheogorath. Sheogorath as seen with Bar Daau and Hermaeus Mora with his unexplainable ability to manifest himself within Nirn seemingly at will and without summon. One wonders by what magic they are able to ignore the Lunar Lattice entirely, perhaps they may have something equal to a dragonborn emperor within their services to overcome it?
Hermaeus Mora is known to present himself often as a wise gardener, tending to the roots of possibility and cutting the branches and sprouts that he sees as dangerous. Very similar to the philosophy of the Psijic Monks. If Hermaeus can be seen as "trimming and guiding" Sheogorath can be more seen as someone who throws seeds around lets the garden grow wild till it all burns to the ground and the process can begin anew and Sheogorath can delight in a new garden with new plants.
Jyggalag and the previous Greymarch is still remembered in detail within the isles from what i've seen, i have a hole in my memories of another prince associated in a similar manner to Mora it must exist but it eludes me? perhaps the act of forgetting the specific solution to the Greymarch is precisely what allows it to happen, Jyggalag being the natural antithesis of Sheogorath emerging from him. Then the act of remembering this other prince must result in a similar event I doubt the resulting aftermath would be pretty so i don't believe i want to pursue this information.
These two Princes, of Amnesia and Memory serve a vital role within Nirn, one creates the other regulates the creation within a ceaseless cycle of manic creation and obsession. They form a fundamental dyad within the universe, anything that effects one must effect the other.