What are Itachi's real intentions of joining Akatsuki? Is he really working with, or against them? I mean I know he destroyed his clan, but he left his brother alive, why? He betrayed Konoha to join Akatsuki, why?
I think Itachi knows some of the secrets of Uchiha Madara if not all. I think he killed everyone in his clan because he knew Madara would seek them out maybe to recruit them or use their power. Since Itachi was the strongest in his clan he knew none of them would stand a chance against Madara, so he killed them. He left Sasuke alive because he had potential to surpass Itachi and he may even have the power to defeat Madara.
Itachi was one of the top ninja not only in his clan but Konoha. For him to just betray Konoha to join a team of renegade ninja, to me, doesn't seem like a good enough reason. Even the Kyuubi stated that Sasuke's power is as sinister as Madara's, so it seems like he has the potential to rival if not surpass Madara. I think Itachi is planning to try and stop Madara or atleast make it so that Sasuke is strong enough to do it if Itachi were to fail. Also about everyone saying Itachi shed tears for Sasuke, I think that is false. I think it was more of him feeling Tobi/Madara's presense and the bad omen of storm brewing(he wasnt crying.)
If Itachi were to betray Akatsuki I think Kisame would help :x
(Note: I can't recall if I was gonna say more then what I did, I was busy while type this so I kinda for got some stuff, LOL) What are your thoughts on this?