I like to say that both Sephiroth and Jenova were working with one another but both thought they have full control.

I've been playing it again so I'm keeping my mind state with the current game events. I love getting into this shit so much. My friend just beat FFVII and I told him to play it again to see all the hints of Cloud not being "Cloud" for most the game because then I can go crazy on him to play others haha. He went through the game rather quick too.