The Detective Agency is filled with good people, the likes of which Kyouka has never been lucky enough to know before now. Besides her and Dazai, not a one of them would survive the mafia - not even Ranpo, though he’d last the longest until someone made an entirely irrational decision to shoot him for mouthing off, his usefulness to the mafia be damned. She’d give it two weeks.
Dazai, though, carries the Port Mafia with him wherever he goes. His ruthlessness may be used for the good of the city now, but she has no doubt that he would resort to the same tactics as the youngest executive in mafia history if he were given cause to believe they would work best, torture and murder included. He wears layers upon layers of masks, ones he doesn’t take off even for the coworkers who trust him with their lives.
Kyouka can never be sure if that trust is warranted, or if the Agency is close enough to a family that even Dazai with his too-black eyes and plastic smile is considered ‘one of them’. She can never tell whether the others even realize that Dazai’s changes are as superficial as swapping out for clean bandages.
But no one knows better than she does that you don’t clean the marks of the Port Mafia off you as easily as you might clean the blood off your hands, and no one wants to prove more badly than she does that there’s a place in the Agency for the cold-blooded killers that she and Dazai were and, on some level, still are.
So she places her trust in Dazai, knowing full well just who it is she’s relying on.
The Detective Agency is filled with good people, all of them good in their own ways. Atsushi considers himself lucky to have met all of them, but the first he met and perhaps the one he’s closest with is Dazai.
Atsushi knows that calling Dazai a ‘good person’ would get vocal disagreement from most of the rest of the Agency, starting with Kunikida and ending with Dazai himself. He knows that Dazai is not a nice person, but nice and good are different things.
Listing all the times Dazai’s been physically injured helping other people doesn’t mean much, because Dazai doesn’t care about his own physical health. Atsushi thinks instead of when he suggested meeting with the Port Mafia to get their help against the Guild, and Dazai - who had the look in his eyes that Atsushi recognized in the mirror from when he thought about the worst memories of the orphanage - had agreed. For the good of Yokohama, he put himself in front of his abuser to ask for his cooperation.
Atsushi is told that he’s a good person on a near-daily basis, but he could never do what Dazai did. Not even for the city’s safety. Maybe not even for the other detectives.
Dazai doesn’t care if people care about him. Dazai expects to be hated by everyone even when his actions are only to protect the city, and he expects his friends to consider him unfeeling even when he’s sitting in a graveyard alone. When someone (Atsushi) expresses otherwise, he’s surprised.
Dazai is reliable in a crisis no matter how much trouble he causes when things are calm. He needles Kunikida almost constantly, but the few times Atsushi’s seen Kunikida genuinely hurting, Dazai has left him be. Whatever Dazai’s reasons for the troublemaker act he puts on are, hurting the detectives isn’t one.
Atsushi owes Dazai his life, but even if he didn’t, he could place it in Dazai’s hands and not feel an ounce of fear.