I don't think Itachi really cares about Sasuke, but rather he wants someone who can fight him equally with his Mangekyou Sharingan. Sort of like training someone up to fight with in a crude manner of speaking.
Originally posted by: AssertnFailure
2) itachi says "the only one who can beat me is another with the same eyes as me." Of course this led us all to believe that he was referring to sasuke....however the only way sasuke can have the mangekyou is to kill naruto...and we KNOW that will never happen.
At the end of their battle - it's possible that Sasuke thought he actually killed Naruto, thus his frame of mind stated that he'd killed his best friend, unlocking the ability. We don't know how it works exactly, but it has to be about the evilness of killing someone you've cared about, and for all we know Sasuke thinks he succeeded in that department.