Only as much as I could dredge up from old texts. According to legend, he fought and bested the dragons, and was in possession an exceptionally powerful soul. It’s said he disappeared from his home in Anor Londo some time ago, but beyond that, I simply don’t know. Perhaps he no longer exists in this world, if he ever did in the first place.
Then again, if there’s one realm in which we could expect to find long lost deities, it’d have to be Lordran, eh?