Quote Originally Posted by NeoCracker View Post
And what were Sephiroths motives exactly?

For some reason or another, he decided to do exactly what Jenova was going to do, and for the life of me I could never piece together why.
Divinity. Power. By wounding the world with Meteor, Sephiroth would be able to absorb the spirit energy unleashed by the damage, gaining immeasurable power, to the point where he could become one with the planet, and with Jenova. He wasn't 'manipulated' by Jenova; rather, he shared some of her nature since he was partly comprised of her cells and her essence. He wanted revenge on the world for its perceived injustices against him, but he also came to realise he could gain absolute power, ruling all life alongside his 'mother'.