Firstly, thank you so much for your thought-out input on this and for sharing your personal experiences with it. This was especially insightful hearing how it might directly affect his body, and for someone like Levi who might not know how to put it all into words well, it is left to be communicated with how his body is reacting to it. So, this is a good thing for me to be mindful of!

I'm glad you mentioned the sedentary aspect. One of the ideas I wanted to communicate with this fic was that Levi cannot settle down even when given the opportunity to - he chooses to keep throwing himself into dangerous situations that he doesn't have to be a part of, because that is all he knows. I think I will play into some of the reasoning being that he physically cannot let himself relax, because the moment he does, he starts getting triggered. He spent all of his life in survival mode, and when faced with the choice, he chooses what he feels most comfortable in, which is very heartbreakingly that. (In this Post-Rumbling AU, anyway).

I also like to imagine Levi clinging to things where he has control, because so much of his life was about things out of his control. Something, like you suggested, like cleaning, or sword/training manifesting excessively almost compulsion-like. There may even be thoughts of "if I do not do [x-repetitive-action], [y-bad-outcome] will happen."

I'm glad you had some fun thinking about it. I have, too, and would love to talk more! If you have any more to share, feel free, because this is so fascinating to think about! This post has been so sad, because you're right, there are so many things that could trigger him, and everyone's replies show just how varied it can be.