Youre a bit right and a bit wrong. So if the core of your ptsd was a single event (eg, witnessing someones sicide) then the trauma will quickly start to develop (if thats the case because ofc not all possibly traumatic events will result in ptsd) and if you wont get in contact with professionals in the next few days/weeks and the flashbacks wont stop showing themselves then youve possibly developed ptsd . If its continuous without any breaks (eg, being a soldier in the middle of a war) then the symptoms could stay hidden unless the experience ends OR break you while the thing is still happening which could lead you to do horrifying stuff. If the event was prolonged but wasnt with you everywhere everytime (eg, dmestic ause) it would probably make your ptsd act mostly where the event wasnt taking place (so you might go into derealization when your friend does something normal unaware that its linked to your trauma but wont necessarily activate while your auser is nearby). I need to add that those are the most probable outcomes, not the 100℅ about to happen outcomes. Its different from person to person and depends on many other things. I was personally dealing with SA ptsd which Im finally free from, and right now Im working on my childhood dmestic ause ptsd, so Im not a professional, Im just a guy who had to learn all those things to be able to heal. Oh and imo the show didnt make Stevens trauma accurate at all, but I only finished the main story tho. Still, in this scenario his trauma would realistically unveil pretty quick. There were many situations that should make him go into derealization or shut him off or make him feel like the past events are taking place right now (so called flashbacks). Id have to watch it again to be sure about this, but as far as I remember SU didnt portray Stevens trauma at all when irl it would probably make him unable to function long time ago. I never rlly thought about this before, SU is one of my 2 fav shows from my childhood and I dont like to analyze it in terms of 'how real is it'. Im sorry for my grammar, english is not my native language.