(Long post!) I have an entire plot in my head with focus on the book "The Island of Doctor Moreau" where Chuuya goes to seek out info and Fukuzawa, Dazai, and Atsushi are there for [insert plot reason]. Basic plot summary is that there's an incident that splits everyone up leading to Fukuzawa with Chuuya. Obviously there's tension between them at first but Chuuya also knows to show respect to the man who runs the ADA

One of the things BSD has always been an enigma to me is the presence of Lovecraft, so this Island is set up to appear as an Archive of Abilities run by Dr. M(onroe) that harbors 'Wayward' Ability users with abilities they cannot control making them incapable of joining normal society. However floors below that house those who were 'Once Humans', which are the unfortunate outcome of failed experimentation on people. Lovecraft would come from this place

I have some ideas I'm messing with for Monroe's ability/history but essentially they unlock repressed memories while trying to survive. They end up having a lot in common which Chuuya slowly feeling comfy enough to ask him for advice as a leader. I'm not quite sure how they'd react to the revelation but I don't want it to just shock them out of no where. At the very least I don't want it so Chuuya is determined to stay away from Fukuzawa bc it would conflict with his place in PM. It's not going to exactly be easy for either of them but they will have a natural progression in their relationship