If you're a Masters of The Universe (MOTU) classics fan, then chances are you'd probably heard or seen/bought the King Grayskull figure through matty's website some years back. He technically appeared in the 2002 MOTU reboot cartoon series therefore he was never really endeared by the MOTU Filmation faithful. Of course, if you've been paying attention to the endless bios that matty/toyguru has been creating with each of the monthly figures release, then you will realise that they have found a way to somehow integrate these non-Filmation/80s characters into the main story line. The King here was somehow mentioned as the modern He-Man's ancestor when in actual fact his design was just an early sketch of He-Man. Whatever.
Although he was such an integral part of the He-Man folklore and that his wife was the legendary first Sorceress of Grayskull (or at least that's what Toyguru wants us to believe), in my canon I'd prefer to imagine him as the 'reluctant' king who led a very easy-going life. In my books, he was a laid-back throne-warmer who lets his days pass by sitting around in his throne drinking way too much. He just sounded and looked better that way.