There is no way this is an original thought but I still need to yap about my head cannon that Yukio stress smokes on and off and the habit gets worse as he gets older, especially because I also see him juggling part time work with The Order while he puts himself through medical school.
And I bet you he absolutely hates being told he resembles Shiro when he stress smokes because he does not want to confront the complicated feelings this observation triggers.












