Just thought I'd make some notes on Jenova just in case anyone wonders what the heck is going on.
1. Cloud is freakin' SCARY.
Sephiroth took control of Jenova's body for the events of the FF7 game, a disturbing experience in and of itself. Then Cloud kicked Sephiroth's butt. This makes Cloud the proverbial "bigger fish," and therefore, something to be avoided or neutralized if possible.
2. Sephiroth never did Jenova any favors.
The only thing Sephiroth ever did for Jenova was cut off her head and take control of her body. He made a big speech about her being the "rightful ruler" of the planet, but what he actually did was cut off her head. Not exactly helpful.
3. Jenova is not a homicidal maniac.
She came to the planet because lifestream was her natural prey, not because she's an evil or spiteful being. She doesn't have anything against humanity per se; they're just sort of in the way. Think Cthulhu here; it's not that he
wants to destroy you, it's just that you're so insignificant you get squished like ants in his wake, kind of like how you can't plough a field without killing a lot of bugs.
4. Mainly, she wants to survive.
Jenova mostly wants to avoid getting killed (again!). Since it's turned out that the humans on this planet are indeed a threat, she's had to get creative. Because Aerith is in the lifestream to defend it, it's no longer the easy prey it was. This means that she will either have to figure out how to overcome Aerith, or figure out a way to survive on a different food source. Since she's incorporated several human organs into her new body, the second option appears to be the best right now. This does not mean she's going to be all nice and friendly; she still doesn't understand humans all that well, plus they're a potential threat. Plus, when they're sufficiently cheesed off, they have a habit of
ganging up on you. They are not an animal to take for granted.