adhd adhdcharacter angst angstwithahappyending autism autistic autisticauthor boyfriendchallenges challenges communication communicationiskey communicationissues crush daisuga death depressionanxiety establishedrelationship fakedatingau fluff fluffandangst funnycute gettingtogether haikyuu happyending has healing healthyrelationship hurtandcomfort hurtcomfort hurtnocomfort impliedpastabuse iwaoi kagehina kageyama kuroken lostlove majorcharacterdeath mentalhealthissues mentionedhomophobia multiplepairings multiships nohappyending ocd oneshotcollection onlyonebed osasunakomo polyamorous polyamory polygamy polyship protectivebrother rareships romance sakuatsu sakusa sensoryissues slightangst tsukiyama tsukiyamakagehina uen