While Akatsuki is calm, mature, and peaceful, his cousin Hanabusa is quite the opposite: being childish, loud, and troublesome (especially to Kaname Kuran and Yuki Cross). The two cousins have been childhood friends (along with Ruka Souen and Kaname), and they frequently played together in the past, becoming close friends. There are many times when Akatsuki is punished by Kaname, along with Hanabusa, whenever Hanabusa causes trouble. This first occurs when he drinks Yuki's blood, as well as causing two Day Class girls who witnessed this to faint out of fear. They are shown together almost all the time and share a lot of secrets together unlike the other relations in the story. As shown in the anime, Hanabusa also likes to challenge Akatsuki to see who gets the most Valentine's Day candy from the girls in the Day Class. Also Hanabusa likes to torment Kaname often and Akatsuki persuades him not to, telling him it's a bad idea but he is ignored and the two get into trouble again.
Aido annoys Kain frequently but on the other hand, Kain makes some comments which torment Aido as well. Even though Kain is seen trying to keep Aido from causing trouble he doesn't show much effort.