This chapter proves it for me. In the past it wasn't clear since they talked on an even tone to one another, even though Kakuzu was always the one warning Hidan. In this chapter though, Hidan actually pleaded for Kakuzu to help him. This is a first for any Akatsuki member (with the exception of Tobi, but then again: he is Tobi). Kakuzu, on the other hand, was all the while casually observing the spectacle and even started mocking his partner like a good boss should. So all in all, Hidan is the bitch. What do you think?