they can be besties (incredibly begrudging older brother & Does She Know) if you believe. believe in iris and her manic pinkie pie dream girl swag. when i say this i say it in the same way i say "they're so in love and boyfriends and married" about ryusaito -- it's about framing and how close the camera is zoomed in. saito "has never gotten over anything in his life" sejima. iris "walking corpse of her bio mom" sagan. but where saito hates manaka, So is haunted by her. and what is saito behaviour if not putting up with shit to harm the object of his animosity. so... i think they can be besties :)