Well, I don't want to spoil it since I don't even know for myself but there were rumors even before I read the spoiler. I'll give you more thoughts in the spoil tags here *beware, I think i really imply the person and just "blurted" it out; if you don't want to know, and I don't want to be blames, don't click the spoiler!!...that is all ):
Click here to see the hidden message (It might contain spoilers)
How does Inferno start? What become of that? I was suspicious here but didn't think apprentice because that isn't apprenticeship, that's using someone. Maybe Caedus thinks this is the only person he can use since this person is loyal to him because of what he delivers in the form of flow walking.
"Changes are nice--but so is continuity!"
"Then you saved my life. How disgusting. How unfortunate."
"No, don't gush on so. It was nothing, really."