Interesting theory Big D. Certainly more plausible than the far fetched R=U.

As far as what Square were thinking when they made the game though I'd say that Griever is just a legendary GF. Supposedly the most powerful of them all. It therefore makes sense that this powerful and evil sorceress from the future went out to try and find him. And she did. She found the most powerful GF and made him her own. Seems perfectly plausible.