FF8 Theory - Ultimecia is...
Here is a crack theory that has no real evidence, just wild speculation on my part. Stop me if you've heard this one, Ultimecia is Rinoa.... 's mom.
Ultimecia is Julia Heartly.
Here's my angle. Julia Heartly was a Sorceress all along, and she tried to keep it hidden, but the Galbadian government found out and tried to kill her. So, she faked her down death and went into hiding to keep her family safe. Caraway would tell everyone she died in a Car accident.
Using her powers, she accidentally teleport herself across time into the far flung future, where hardship and loneliness drives her mad. She masters her sorceress powers, growing ever stronger, until she decides to remake the universe as she sees fit, and begins her plan to cause Time Compression.
It kinda fits... I mean Edea was like "mom" to 5 of the main cast, the one that wasn't, her mom is the main antagonist.
And there you go. Spread it around, if you like it.