The Calamity from The Skies(SPOILERS!!)
This should clear up pretty much everything to do with Jenova in the story
Two thousand years ago, an alien fell to earth. Its purpose was to absorb the Planet's spirit energy before moving on to its next victim. It befriended the Cetra (or the Ancients), who shared all their knowledge and wisdom with it. It was from the Cetra that the alien learned of Meteor; the Ultimate Destructive Magic. After settling into their society, the alien spread a disease throughout the Cetra, killing all but a few. The survivors managed to overcome the alien, and they sealed it away safely deep beneath the earth where it could no longer pose a threat to their civilisation.
Thirty years ago, Professor Gast of Shinra uncovered the preserved body of the alien. Believing that it was the last surviving member of the Cetra, he named it Jenova, and started up the Jenova Project; a process which involved injecting Jenova cells into members of SOLDIER (Shinra's elite army force) in an attempt to create a legion of unstoppable fighters that possessed the powers of the Ancients.
However, Gast's assistant - Hojo - had more sinister plans. His lover, Lucrecia (the former lover of Vincent Valentine), bore a child. Against Lucrecia's wishes, Hojo injected Jenova cells into the unborn foetus. The result was a being of extraordinary power and intelligence. Hojo named the child Sephiroth.
After the incident at the Nibelheim Mako Reactor - where Sephiroth claimed the head of Jenova - Hojo transported the torso to the Shinra Building in Midgar. When Cloud, Tifa and Barret sneak into the headquarters to rescue Aeris, the body mysteriously disappears from its chamber, and the President of Shinra is found dead. Recognising the murder weapon (the Masamune; Sephiroth's deadly blade), Cloud vows to pursue Sephiroth and avenge the terrible things that he did in Nibelheim. Along the way, he must fight four forms of Jenova: Jenova BIRTH, Jenova LIFE, Jenova DEATH, and Jenova SYNTHESIS. The first three forms are various manifestations of Jenova's torso, whereas Jenova SYNTHESIS is the head.
Jenova has two missions in Final Fantasy VII. The first is to gather each and every cell that Hojo injected into his test subjects via a process known as the 'Reunion'. Because he was injected with Jenova cells after the incident at Nibelheim, Cloud is participating in the Reunion. When Jenova's body escapes from its containment, it assumes the form of Sephiroth. Cloud, believing that the actual Sephiroth has returned, begins to pursue it - oblivious to the fact that he is merely being drawn to the Northern Crater in the same way that the black-caped men - Hojo's other test subjects - are.
Jenova's ultimate ambition is to obtain the Black Materia so that she can summon Meteor and destroy the world. However, the Black Materia resides in the Temple of the Ancients. Cloud, whose Jenova infusion was not completed due to Zack's interference, acts as Jenova's puppet. The evil alien draws him towards the Temple, whereupon Cait Sith sacrifices his own life to obtain the Materia. Cloud then heads towards the Northern Crater, believing that he is pursuing Sephiroth when he is actually doing Jenova's dirty work. The death of Aeris at the hands of Jenova - the end of the plan to summon Holy - merely serves to fuel Cloud's hatred for Sephiroth, although the true Sephiroth had nothing to do with the incident.
When Cloud hands the Black Materia to Sephiroth, the head of Jenova is liberated at last. The Reunion is over, and Jenova can begin to combine with Sephiroth - a process which leads to the existence of Jenova SYNTHESIS, and ultimately to the birth of God himself: Bizarro Sephiroth. However, Cloud and the team manage to defeat this manifestation of the evil duo, and Sephiroth draws on Jenova's power to become Safer Sephiroth: the one-winged angel. The defeat of Safer Sephiroth extinguishes the power of Jenova from Cloud's arch enemy. Weak and helpless, Sephiroth is slaughtered by his rival's Omnislash, and evil is vanquished from the world.
If there's you have any problems with this, well SHUT UP!!! its my first thread here
and please don't someday manage to turn it into Tifa vs Aeris.
and to prevent confusion I did not right it I stole it.
