Thanks to Tinfoil_King for the inspiration!
Sephiroth’s probably the first villain everyone familiar with Final Fantasy can think of. Before him, most Final Fantasy villains were like the Shinra executives. Palmer was like a heavyset Kefka. Heidegger was like a bumbling Exdeath. Scarlett was like a seductive Cloud of Darkness. Only the President was sinister, and he was nothing to Sephiroth.
Every moment he was on screen, you could feel a chill down your spine. Maybe it was his theme song, his menacing stare, or cold, murderous behavior. He was a threat from the first time we see him. And who could forget his most iconic scene, where he burns down an entire village and smirks while walking into the fire. Kefka was scary because he was unpredictable. Sephiroth was scary because he was calculating.
We’re searching for him, but he knows where we are. In fact, he meets us when we least expect it, not the other way around. He’s in complete control, including over our main character. We have many battles with his avatar. But we never fight him directly throughout the entire game. Tinfoil_King outlines why here:
I could never find where I first saw this theory. Basically, in FF7 you never fight Sephiroth physically.
1) Every time you see him, and it leads into battle, what you fight is a chunk of Jenova, iirc. Maybe once or twice a clone.
2) The one time you a certain you are seeing the real Sephiroth he is trapped in a crystal.
3) He famously destroys the solar system. Repeatedly. Yet…need meteor? This is an example of a mental projection. Looking at this and above it begs the question if he is even physically fighting you or if this is either a mental hallucination that seems real or entirely in the minds of the party.
4) As he gets weaker/beaten he goes from attacking 9 to 3 to 1. The last one is the most telling. He is suddenly back to a normal looking human. After the duel Cloud’s alone in the dark void where he fought Sephiroth when a hand appears. Suddenly he realizes he is, just standing on a rock just within reach of Tifa.
This is helped and hurt by the spin-offs. Advent Children helps when Sephiroth takes over Kadaj. Before Crisis mucks it up a tad with Angeal and Genesis’ transformations and other things making some of the stuff he pulls plausible.
Tinfoil_King suggests that what we fight are just a series of illusions. Sephiroth fell into a Mako Reactor and somehow ended in the Northern Crater. But through sheer willpower, was able to appear in several forms, all around the world. We’ve seen villains like this in Final Fantasy before. Final Fantasy IV had Zeromus; his mind control was so powerful, he was able to use a powerful magician to control other. Ultimecia was able to do the same, using her witch powers, to control potential sorceresses. But Sephiroth, having pure Jenova Cells, could control anyone else with the same chemical makeup.
Or was it purely Sephiroth? I can’t find the exact theory Tinfoil_King references. But perusing /r/FinalFantasy, I think this is pretty close:
My understanding is that things are more clear in the Japanese translation of the game, and we’re supposed to realize as the game progresses that after Sephiroth is stabbed by Cloud in the Nibelheim incident and falls into the lifestream that’s pretty much it for the real Sephiroth’s body, which eventually we find crystallized in the northern crater. All of the times that we encounter “Sephiroth” from that point on is actually parts of Jenova, who is a powerful shapeshifter. Jenova breaks out of her containment cell in the Shinra building, takes on the form of Sephiroth to hide her true identity, and then you spend the rest of the game chasing after who you think is Sephiroth but is actually Jenova. This is why whenever you encounter “Sephiroth” in your chase of him you actually end up fighting a Jenova monster and a piece of Jenova can be seen after the fight disappearing. This is also why “Sephiroth” is able to manipulate Cloud into giving him the black materia, because that’s actually Jenova manipulating Cloud who has Jenova cells in his body and therefore is vulnerable to the influence of Jenova. The plot of the game gets very complicated and the mangled, dumbed-down version of the plot we get in the US release seems to miss a few key points of the explanation of what’s going on. Sephiroth is never the real antagonist of FFVII, Jenova is.