As always, I love how Hiei and Kurama always provide the commentary on each other’s fighting. In particular, I like the contrast of irritation: in Hiei’s fight, Kurama was exasperated (in his placid Kurama way) with Hiei’s insistence on bravado and spectacle. On the other hand, Hiei is clearly irritated with how Kurama always holds back until he knows his opponent’s strategy backwards and forwards. They both have points. Kurama’s careful strategy leaves him needlessly vulnerable at times when he was clearly stronger than his opponent, and Hiei’s “strategy” lacks, well, strategy. It’s all noise, and the only reason Hiei still lives is because he can back up his words in most cases.
Anyway, it’s just a great way to develop both of their characters as well as their relationship, because it says something about how they work together that they understand and know each other so well.