Sephiroth is a 35 year old member of SOLDIER.  He is the villian of the game, even though you don’t meet the real Sephiroth until the end of the game.  Sephiroth grows up thinking that his mother, Jenova, died shortly after giving birth to him.  While on a trip to Nibelheim with Cloud and Zack, Sephiroth is tasked with investigating a malfunctioning reactor.  Inside, he discovers that Shinra is creating monsters, and finds a door with “Jenova” written over it.  Sephiroth starts to wonder if he was created in the same way as the monsters found in the reactor.  He secludes himself in the Shinra Mansion, reading research reports all day and night.  Cloud then confronts him in the basement, and Sephiroth explains that he was produced by Professor Gast using Jenova cells.  Jenova was an Ancient that was excavated by Shinra, and now kept in the Nibleheim reactor.  He tells Cloud about a disaster thousands of years ago where Cloud’s ancestors hid, and allowed the Ancients to die. Believing to be the rightful heir of the planet, Sephiroth burns Nibleheim to the ground and heads for the reactor in search of Jenova.  Inside the reactor, Sephiroth attempts to free his ‘mother’ and in the process wounds both Zack and Tifa.  Cloud confronts Sephiroth inside the reactor, and manages to defeat him and throw Sephiroth into the Lifestream.  Five years later he returns to exact revenge on Shinra and claim his rightful spot as heir to the planet.  His goal is to find the Promised Land, an area rich of Mako energy, where he can absorb all of it and become a God.  He eventually summons the black materia, Meteor, to fatally wound the planet so that he can be at the center of all the energy.  We come to find out that the real Sephiroth is stuck in the Northern Crater, and that the Sephiroth we have been seeing throughout the game is just his projection.

“You are just a puppet… You have no heart… and cannot feel any pain… How can there be any meaning in the memory of such a being? What I have shown you is reality. What you remember, that is the illusion.” – Sephiroth