Sephiroth, his own man or a puppet?

Now he want to avenge his ppl the Cetra ! His life is the chance to set thing the way they were suposed to be !

Once again, he just learned that he was a Cetra. He has no emotional involvement with them whatsoever, so his instant reaction of "I will kill everyone in the world!" is bogus.

I have Russian in me. I learned this a few years ago. I didn't freak out and start killing people and committing arson because Stalin murdered a couple million of my distant relatives decades ago. The idea of Sephiroth going from "honorable hero" to "murderous supervillain" by himself, with no help from Jenova at all, in the span of 24 hours, for those reasons is retarded.