[Nogitsune]

I agree, but I don't think that's anythign special.
If Lelouch's plan was simply to enslave everyone - which, of course, it isn't - then everyone would try to stop him, not only Kallen.
And if people found out about Lelouch's real intentions, then there would be many who'd try to stop him.
Sure, Kallen would be one of them, and I'll cheer for her, but I don't think that she will ultimately save him all by herself.
The way I see it, Suzaku will stand by Lelouch until the end, and therefore play a large role in how thing will turn out for our favourite emperor - even though he's quite messed up himself. And then there's his little sister, who is not as naive as people think she is and loves her brother more than anyone else, no matter which side she seems to be on at the moment.
I don't say that Kallen won't play an important role, but I doubt that she will do anything overly dramatic - like saving Lelouch with the power of her love.
If it took just someone who loves Lelouch to save him from the path he's chosen, then Suzaku would suffice. Or Nunally, since Suzaku is an expert in making sacrifices himself.
Hm... then again, if Nunally doesn't hurry, Kallen might really just take things into her own hands and throw something at Lelouch.
Throwing things always helps.