[Sasuke nods to Itachi to show he had heard, expecting him to go on ahead. Even though it might be faster to carry Law just like how Itachi was carrying Bepo, it's not really something that occurs to him to do. Sasuke might be an inconsiderate jerk, but some things were just matters of pride that weren't messed with.
More importantly, he hears someone in the stairwell.]
[action]
More importantly, he hears someone in the stairwell.]
Someone is coming.