Sasuke has always looked up to Itachi and from the moment he heard why his aniki had really murdered his clan, he wanted answers. Then he suddenly sees his dead brother alive again. Of course he's going to stick with him and want to hear his answers. Plus the reason why Sasuke doesn't fight a lot against Kabuto is 1) because he would probably fight to kill and he was told they need Kabuto alive and 2) I think he wants to see what kind of jutsus Itachi knows. I mean he just got to hear about that Izanami and he doesn't know anything about while his brother does. Of course he wants to see what that jutsu is going to do and if he keeps attacking Kabuto, he will have trouble seeing the jutsu unfold. Plus Itachi specifically told him to stay with him. Even after all those years of hating him, I think that deep inside Sasuke still trusts his brother. That's why he listens to Itachi now. Not only because he is his aniki but also because Itachi is still more experienced in fighting and as shown in the manga, he knows a jutsu that Sasuke didn't even hear about before this fight.
Plus Itachi protected Sasuke because he's his little brother. We know that Itachi loves his brother and would do anything for him. That's why he protected him even when it wasn't necessary. That protection was his natural instinct as an older brother who thinks his younger sibling could be in danger. He probably realizes that Sasuke isn't that weak little kid anymore that he needed to help train and protect, but instincts are hard to lose.
I'm a Sasuke fan and I don't see what's wrong with his character now. At this moment he's confused, he wants answers and he can get them from his brother who came back from the death. Give the guy a break and forgive him that he isn't trying to kill anyone who he sees for the moment -_- At this moment he looks more sane than he did at the beginning of the war which is an improvement in my opinion. And now I wonder who read this whole post LOL
+rep)
