After Dazai up and abandoned the Port Mafia, Mori took it upon himself to find a replacement. It took a while, but he did it. And he couldn’t have chosen better. When Dazai heard about you and the rumors circulating, he felt the urge to meet you for himself.
He managed to find you in the middle of a mission you were on. He chose not to get in your way, silently observing until the job was done, a heap of bodies left in your wake. It seems you’re good with a gun. That soulless eyed expression is so familiar to him. He feels as if he is staring back at a younger him, but worse. He wasn’t aware that was possible, until now.
He isn’t intimidated of course, impressed if anything. It isn’t every day he meets an individual who could rival him and have a chance of coming out on top. Much less a teenager.