immediate or early symptoms:

he struggles to remember what actually happened to sustain the brain damage, he does have some awareness of what happened but he cannot remember it clearly

a lot of zoning out and staring off and looking generally dazed and confused, especially in the early days of recovery

he couldnt handle being in a car for the longest time and had to take it really slow with learning to fly as a green lantern because of motion sickness and nausea. it went away eventually but it really fucked with him for a bit

horrible horrible headaches and migraines that dont go away long-term but just got less severe over time. same with neck pains and head pressure

he had a very noticeable delay when responding to questions that make people think he was not paying attention on purpose or not listening, people repeating themselves only made him have to delay again to respond

foggy feeling / foggy thinking that lead him to a lot of bare impulse decisions in some early days. cannot think things through if you can barely think, and you cant process how you feel about your new circumstances if you cant tell what youre feeling.

symptoms i think hed still have long-term:

change in taste and smell, he starts enjoying foods he never used to and hating ones he always liked. he doesnt notice until h-girl points it out. his smell is just bad. he can barely smell anything including himself.

difficulties concentrating in general but especially in hand with difficulty reading. acquired dyslexia for sure. he constantly is asking terrific to read stuff to him because he just cant stay patient enough to get through the jumbles

short term memory issues like forgetting where he put things, but i think its mostly that he misremembers conversations or forgets them entirely

executive function issues. it almost makes people think he has ADHD or ADD (and he likely does) but theres obviously something more going on.

on the ADHD/ADD and TBI symptom overlap again i think hes highly distractable once he regains his general ability to focus in conversation. constantly jumping topics, you can get him to forget he was talking about something by bringing up something else, it just has to be of interest to him or he'll double down on the initial topic

gets tired for no reason sometimes. king. also has bouts of insomnia maybe. if he cant sleep he'll do tasks and chores around the HQ to his best ability

he is sooooo sensitive to loud noises i think he wears something to dampen sound while hes out and about. constructed ear plugs for the overstimulated princess