Thanks to RichtersMask for the inspiration!
My theory is that in FFIX, Necron was possessing Kuja. The devs seem to try to play it off like Necron just comes out of the blue, because of Kuja’s fear, because of all the war that had happened up to the events of the game, or just because of the cataclysmic power of Kuja’s Ultima finisher, but I think that Kuja’s actions and his unusual spiritual state (can’t achieve trance, can’t properly feel emotions) as well as the casual way he treats all life, with nothing at all being important to him, represent something of a not-thereness to him. I think Kuja isn’t really in control of his actions, and that if he was he wouldn’t seek to destroy Gaia and Terra, just Zidane, who he hates, and Garland, who he may or may not even hate more. It would also explain how he managed to become so powerful.
Final Fantasy is no stranger to mind-control theories. In Final Fantasy II, the Emperor might have manipulated Leon. In Final Fantasy III, Cloud of Darkness manipulated Zande. In Final Fantasy IV, Zemus manipulated Golbez, who manipulated Kain. In Final Fantasy VII, Sephiroth manipulation Cloud, and in Final Fantasy VIII Ultimecia controlled Seifer, Adel, and Edea.
…but did Necron posses Kuja?
If Necron did control Kuja’s mind, then he created the situation that would justify his destruction of all life.
“All life bears death from birth.”
“Life fears death, but lives only to die.”
“It starts with anxiety.”
“Anxiety becomes fear.”
“Fear leads to anger… anger leads to hate… hate leads to suffering…”
“The only cure for this fear is total destruction.”
And the fear that Kuja felt wasn’t his own (but it was). Kuja’s powers seem supernatural:
Kuja is largely immune to injury; even Bahamut’s attack barely draws blood from him. Even when not in Trance, Kuja can cast the powerful Flare Star, making him one of the most powerful, if not the most powerful, magic practitioners in Final Fantasy IX.
After entering Trance Kuja’s power increases exponentially. He knows the strongest spells of the game including Curaga, Holy and Flare and Flare Star. He destroys Terra with Ultima and uses it as a final attack when on the verge of defeat.
We don’t know how Kuja entered Trance since only those who feel emotion can do so. Kuja does feel emotions though, even though he had no childhood to do so (…?).
But Necron didn’t need to posses Kuja for the latter to be cold and callous. Kuja is a grand narcissist who couldn’t imagine a world existing without him. And his power was due to him being an Angel of Death (like Zidane).