But how does that show that he was mortal before?
I mean yes the CoC mantled into him, and the CoC was mortal, but it doesn't mean the very first Sheogorath was mortal.. no?
Granddaddy Sheogorath once sat me upon his knee, when I was but a wee sweetroll. He looked at me, perhaps somewhat hungrily (I credit my delicious glaze; I always did come out of the oven perfectly toasty, back then), and told me a story. His Name, he said, swallowing back the extra saliva, was a family heirloom of His. He made sure he passed it down to Himself when He was getting tired of it... I thought that seemed a tad ingenuous of him, as I felt that an inheritance was something you weren't supposed to give away until you were dead, not just tired of something and wanting to get rid of it, but I was just a sweetroll at the time, and godly matters were several crumbs above my ken. He seemed to imply, by his phrasing, that his Name had been passed down many generations ("every thousand years or so", was close to his exact phrasing; like I've mentioned, I was but a sweetroll, and words didn't stick as well as the dust on the floor from that one time he dropped me).
Now, naturally, I outgrew my sweetroll phase, and spend my days as a doorknob (although I
have gotten many complaints about my efficacy as such, and they're starting to get to me), and my nights as the Night Mother, but I'll never forget what Granddaddy said next: "Now open wide, me lad, I'm getting hungry."
---Ms. Theodora Icot, a homeless widow of Windhelm, on her way to the Shrine of Talos for her daily soup