For starters, Ruma Camoran apparently lived up to "not following the Dagonite road" -- she was apparently waiting in Chorrol , judging by unused markers around the fountain, and may have taken part in the charactergen dungeon sequence. Perhaps most interesting is that she was a Blades agent ("Baurus is your boss..."), though she was by no means friendly -- her sequence seems to escalate to the point where she is on the verge of killing the player, and demands that he beg her to take him to Jauffre.
That's the most surprising revelation; other than that, Martin (called "Martyn" then) may either have been captured by the Mythic Dawn or been a Mythic Dawn member himself (the dialogue suggesting this is a sparse "Take me to Martyn." for MQ07, which is "Spies" in the finished game -- going by an unused Mankar/Ruma conversation topic, "Dagon Shrine" may have been MQ07 at some point).
Eugal Belette was the author or perhaps merely the owner of something called the "Mythic Dawn Postulates" (an early Commentaries? Or perhaps just Eugal explaining the Mythic Dawn's beliefs); an unused "Camorans" topic may (this is entirely conjecture) have linked Mankar and his children with Celia Camoran, mentioned in "The Ultimate Heist." There was an Argonian (as the editor IDs insist, though his name sounds more Khajiit) Dro'fahr from whom the player bartered a Great Welkynd Stone, and Martin's legitimacy seemed to be in greater doubt:
"To prove he is the true heir, an emperor must first light the dragonfires in the Temple of the One in the Imperial City. Only the true heir can light the dragonfires, and if he has the Amulet of Kings. Akatosh, the Supreme God of Time, gave the Amulet of Kings to St. Alessia, the first emperor, as a god-certain test of the true heir. The Great God of All made a covenant with St. Alessia. So long as a true heir ruled the Empire, the Great God swore to protect the Empire. The very foundation of the Empire is the bond between god and emperor. That a false heir might be crowned... that the test of the Great God might have failed... My heart fails me. It is unthinkable." -- Jauffre (the only piece of recorded dialogue from this that seems to have survived)
Compare Martin at the end of "Paradise":
"Belongs to me? The Amulet of Kings? So you and Jauffre have said. If it is true, if the Emperor really was my father, then I should be able to wear it. Only those of the Septim blood can wear the Amulet of Kings..."
Does anyone else have any information on what was cut and changed from Oblivion's original main quest?