Second time I've ever seen Akutagawa apologise was before he was supposed to "kill" Atsushi here.

I like how out of all the known generations of duos in BSD, SSKK/Shin Soukoku (I still don't like this name for them as a more yin-yang sounding one sounds more suitable.) they harbor the least amount of hatred toward each other at least after some time, or are just more likely to end up being the "successful" duo. Especially considering that one interaction in Beast... They could get along without even fighting.

With Fukuzawa and Mori its like they're on complete opposite ends, they in the past and now do not get along.

With SKK/Soukoku/ Dazai and Chuuya, they haven't gotten along but could work together when they had to. They still have an amount of hatred in their complexity, or just could never work as "friends" after everything that has happened or during all that has, despite the trust that has built upon years of working together.

Then there's Akutagawa and Atsushi... At first it was confusion, then hatred from Akutagawa, then Atsushi firmly not liking him, to Akutagawa understanding, to Atsushi still being confused but not completely firmly disliking/getting along with him through their team-ups and the fight with Ivan despite their verbal clashes during that time. To Akutagawa being there on that battle with Fukuchi when Atsushi was alone, to the trust that built for the battle as comrades for that one time in that second they needed to defeat Fukuchi.

I don't know what they are now, and I await the day they become friends even if it happens when one of them dies. But they definitely had more of a journey of understanding and not liking views, of jealousy, of defeat, of strength of self, of willpower, of survival, of trust, and of life and death.

Asagiri really makes some interesting and well-written character duos.