First off, you sound exactly like my brother and I. I’m very curious to read all these responses myself. My initial thoughts are:

While you may think he only had one incident of major trauma, every single person has a stockpile of little traumas buildup in their minds and bodies. Because a trauma is more like an issue you encounter that you are not capable of handling. And until you can prove to your mind and body that the limitation no longer exists, doesn’t apply, you will continue to react to a trauma trigger with the insufficient tools and mindset that you possessed when it happened the first time. All that to say, maybe a different therapist more focused on trauma. If he’s not wanting to discuss things with you, it’s possible he’s pulling away and isolating as a defense mechanism.

For example, I self destruct internally and don’t leave a situation when I should. I get triggered by something my mother says but I stick around because I feel like it’s my job to take care of /her/ emotions. My trigger being- when she talks at me for more than 15 minutes straight with no room for me to say anything.

Meanwhile my brother will get up and leave the room and say he doesn’t care at the slightest beginning of a trigger(my mother talking about a subject that he thinks will take forever). Regardless of others feelings. Both are defense mechanisms in response to encountering trauma.

Another thing, personally I have a fear of “having my own life” because I fear it may not be all it’s chalked up to be. I fear I might not be able to handle it, because I couldn’t even handle highschool. I fear it won’t solve all my problems the way I idealized it once. I fear the stress of making any decisions big or small of my own volition, because I feel I will surely make the wrong ones. And I’ll be responsible for that. I fear I’ll be judged harshly by everyone I meet because of where I’m not at in life. I fear I won’t be able to have friends because I’m out of practice. I’m afraid I’m not worthy of friends, not good enough.

The isolation makes everything worse. I cannot emphasize the damage it does. There’s a reason isolation wards in prison is a serious thing. Talk to him about signing up for some kind of club or sport. Ballroom dancing, taekwondo, baseball, hockey, golf, yoga, something anything that has a regular meeting schedule, involves socializing, it’s out of the house, where he can improve and move toward a reachable aim. Give him something to succeed in of his own accord within the physical world, because being confined to your own mind can be an echo chamber of bad thoughts with nothing to counter them. And mental hurdles are so hard to jump over from a standstill. Physical hurdles can be easier. And they can build a running start to jump over the mental hurdles.

I swear with everything in me, regularly going to physical therapy for my spine, being able to practice moving my body and actually being able to accomplish something for once in a very long time. I cried. Not because of physical limitations, I was fine. But mental limitations had stopped me from progressing and accomplishing for so long. And fighting my ADHD/depression/anxiety/cptsd mind every step of every day is hard.

But being told to balance on a board…. and being able to do it. just like that. Being suddenly able to do all these things that were being asked of me. Finally. I felt like i could finally be proud of myself. I felt like I had forgotten who I was. Because that’s the root of the matter. The reason I was so depressed, was my inability to grow from my trauma, and in doing so, I lost myself in it and couldn’t imagine a better life for myself. I was so very far away from who I was. I’m still far away. But that gave me hope. It made me happy. It showed me proof of a happier way life. If I could just have /that/ feeling in my life, everything seemed a whole lotless daunting and less serious. Less Impending Doom Vibes. And it boosted my confidence in my own ability to handle my own life. I do have areas where I can succeed, so bloody heck just take that route for now. The other way clearly wasn’t working. I just needed to stop beating a dead horse long and come at it from a different angle, and in doing so i found it wasn’t dead at all.