im gunna go out on a limb here and say Jenova
Towering for all to see: You first meet Jenova in the Shinra Tower.
Initially is all we know: all you see is her body sleeping in the tank.
But an expert testifies: Cloud tells the others that Jenova was originally in the reactor at nibelhiem.
To Hypnos' dominion: Cloud is under a spell of controll by Jenova.
