I worked with a lot of veterans and quite a few of them had TBIs. They would usually tell you up front, but after a while of working with them you could kind of learn the patterns of someone who had one. I didn't work in a medical setting but rather one that required paperwork to be filled out and procedure to be followed. A lot of them had voc rehab aides that helped them, but some didn't.
Sometimes it was difficult to help them, though, because some of them would get really volatile and abusive or forget your instructions literally 2 minutes into the conversation, then call back to go over the same things for an hour. I think that's one of the worst parts of TBIs. They are living the only life they can now and interpreting the world the way they are because that's how the brain works, whether it's running properly or not. The brain is an enormously complex organ, and it doesn't take much to injure it in multiple areas which can have a huge effect on your life. There's already enough of a chance for the internal wiring to be haywire without throwing actual physical injury in there with it.
Outwardly they may look like normal people but speak really slowly, or forget things immediately, or go from 0 to 100 in terms of anger really quickly for no reason. Regular people just see a nuisance but the reality is that they can't help it. My experience working with them has taught me not to be so quick to judge others and now, while I would never outright assume/ask, if I can start to pick up the queues that someone may have a TBI or issue I know better ways of working around it.
Just don't fucking ride a motorcycle. You could be the safest, most skilled motorcyclist in the world and still die because some other guy is drunk or sleep-deprived or just a terrible driver and hits you accidentally. Many motorcycle accidents are completely not the fault of the cyclist, but its usually the cyclist who is crippled or dead off it.
Source: I worked for an ambulance company as an EMT and some of the saddest, most terrible cases I saw were motorcycle accidents. Even if you live through it, you probably won't be having a good life.
That's a very heartfelt comment somewhat ruined by OPs username...
This is why I don't ride a motorcycle. What if there's some rock in the road that just so happens to look flat due to the sun? Bam, traumatic brain injury. Not worth it.
Flowers for Algenon was a great analogy for TBIs, imo
This is interesting because George RR Martin credits Gregor "The Mountain" Clegane's testiness (he once murdered one of his own vassals for snoring), chronic headaches, and utter cruelty as stemming from repeated jousting blows to the head, resulting in personality-deprecating brain injury. This makes so much more sense after reading the linked post.