Think about how, in the redguard creation myth, spirits circumvent being eaten by Satakal (who continually eats itself) by moving at strange angles. Similarly, Alduin eats the world. The Leaper Demon King moved at strange angles, or "jumped" as it were, to circumvent this cycle of devouring, skin shedding, devouring, and so on. As for his relationship with the greedy man, who better than the King of Leapers to hide parts of the previous kalpa and stick them onto the new one?
So the Leaper Demon King might have leapt all the way into Oblivion? Maybe the Mythic Dawn were onto something. Whatever the answer, Dagon does seem tied to Tamriel more than any other Prince. Regardless of what the plot of Skyrim brings (if too many of the concepts of central Elder Scrolls lore find themselves reduced to a handful of tropes) I do hope we get some in-game books that explore further the trinity of Alduin, The Leaper Demon King and good old Doom Drum. Even, no,
especially if its MK authored and leaves us knowing less than we did before.