I have always thought of Dazai as a person awfully smitten with Chuuya(ofc headcannon), with or without realising (I def go for the oblivious dazai lol cauz he is an idiot). Like he was probably so awestruck when they first met that he couldn’t take his eyes off of him and he didn’t understand why. So he would cling to Chuuya, insulting and joking around cauz he never understood why.
Dazai who hides his emotions away under a steel mask meeting Chuuya whose every minuscule emotion is out on display. Dazai who doesn’t know of the warmth of a person; heck he probably never had friends and Chuuya who is brimming with endless warmth to offer to all his people, so fiercely caring and compassionate that dazai felt like he was going to burn. Dazai who believes he doesn’t have a heart and Chuuya who wears his on the sleeve.
Chuuya was a compilation of all the unknown and bizarre things of this world to Dazai, and he couldn’t help but stay beside him to just watch. Watch this odd creature whose heart was big enough to contain all his people, because honestly dazai was at a loss. How could someone ever be so.. human afterall-