First off, Calvin: Jenova was only encased by the ENTIRE race of the Cetra, thousands of them. And she killed off almost all of them in the process.

And what about Sephiroth? He spent 5 years swimming in the collective consious that is the planet. I'm sure that he has gained more than just knowledge from that experience.
Cloud spent who-knows-how-long in there as well, and didn't gain any of it. Plus, if it was that easy, why wouldn't he, and many others, have jumped in the mako themselves? Mako is NOT Lifestream.

I've played through the flashback many times, and for your benefit I even went through a script of it. The best Sephiroth shows is "Out of my way. I'm going to see my mother". He's never in any daze hearing Jenova call out to him.
Why would he do that if Jenova wasn't calling for him? And you still haven't said how he went from "I must free mother" to "I must kill you all; you're traitors to the Cetra!"

I stick with what I said. Why say "It was all Sephiroth's doing" if he's only referring to part of what he mentioned. It makes no sense. And as for why it's fact -- it is clearly the "big revelation" scene, and is never later disputed. Nobody ever corrects Hojo's claims later on, it is pure fact.
Again, pure assumption. THINK. He's TALKING about the Reunion, he ONLY knows about the Reunion.

Again with "Insane". Evil does not equal insane. Anyway, he does have a strong will, and I'll back this up soon.
It's stated in the game by Cloud that Sephiroth went insane in Nibelheim. Since it was not refutted later in the game, by your reasoning, it must be pure fact.

Maybe the Jenova parts didn't act on their own. Maybe Sephiroth was still controlling them when they fought AVALANCHE.
And why would he control his mother?

I've showed you mine. Now you show me yours.
That "power of Jenova" quote I stated before. Jenova has the power to manipulate ALL minds, including Sephiroth and Cloud's.

That's not stealth, that's "Not being a loud ass". Unless he was actively hiding, he wasn't being stealthy. And considering how many people knew Sephiroth was about, I'm pretty sure he wasn't hiding,
Then how come NOBODY recognized him? Only the executive Shinra guys an AVALANCHE knew he was even moving around.

Read through FFVII again: show me the proof it's about Jenova. She hardly even gets any mention after disc 1, but I suppose you'll say that was all part of the writers' master plan
There wouldn't be an FF7 without Jenova. Sephiroth could have been substituted with anyone with Jenova cells; his connection with Cloud just made the story more endearing. Jenova and her cells is the story.

Cloud's task was also to deliver the Black Materia. I'd say Sephiroth wanted him there more, y'know for the whole BEING STABBED BY CLOUD AND ALMOST KILLED thing. The brainfeck (I can't believe that word is censored) was nice revenge IMO.
If Sephiroth wanted revenge, why didn't he kill Cloud? He certainly had the chance.

1: There's never any reason given why jenova would want to manipulate Cloud. I know you'll throw that "but she WANTED him at the reunion" - but you'll have to prove it first.
2: Sephiroth is probably gonna be a lot more conspicuous than some blob monster.
3: Why?
1. To deliver the Black Materia, as you have mentioned. Whether you believe it was by Jenova's design or not, Sephiroth wanted the Black Materia at the Reunion.
2. Then why didn't anyone notice him in Disc 1, huh? Because he was being stealthy. A human being can be stealthy, a gigantic monster cannot.
3. Well, Sephiroth was a well-respected SOLDIER and a great Shinra general. Can't you see how she could use that to her advantage?


Ah but you're assuming Sephiroth can talk to Cloud because of his cells -- I say, where's the proof? I believe he does all his manipulation with his strong will.
If Sephiroth could manipulate anybody because of his strong will(why does he have a strong will? He's human, except for Jenova cells. Whatever powers you grant Sephiroth you must grant Jenova in greater power), which he doesn't really have 'cause he's insane, then how come Sephiroth didn't just control everybody? Why didn't he overtake AVALANCHE? Why was Cloud the ONLY person in the group he controlled?

Lastly, concerning your quote, if gaining the power of gathered Lifestream was his sole concern, then why didn't he just stay down there and gather?