Sunny felt that there was a hint about what manner of a creature Mordret was in the fact that only the Lost and human Echoes had been allowed to guard him, but that was too little information to make a guess.
What else did he know about the man who called himself the Prince of Nothing?
He was reasonably sure that Mordret was a human… or at least had been once, at some point. A Nightmare Creature could fake a human voice, but not the knowledge of the waking world that Mordret had shown. Sunny also felt that the mysterious prince had told the truth about conquering the First Nightmare at twelve years of age.
Other than that, all Sunny had was the description of the Cruel Sight, which told of a prince that had been given away to a monstrous Dreamspawn, and later returned only to find out that he wasn't welcome in his father's home anymore. That and the fact that the Mirror Beast had been created by Mordret, much like Saint had been created by him.
That was not much to go off of…