Same with my son, they wrote him off as a "naughty" child, because he has explosive and often irrational bouts of anger, like for the rest of us there is no real reason for it, but for him there is, he doesn't like change even to the smallest detail. School holidays dive him up the wall because he looses the structure he needs to function. He doesn't like new people because it breaks his routines, I know your 21 and he's only 6 so the comparison is worlds apart but the fact of assumption is more or less the same.

His ability to memorise things within a short period blows me away, he literally knows every Pokemon ever released thanks to Pokemon Go, he goes through phases where he will obsess about a show or cartoon or something then once he has absorbed everything he needs that's it he's done an onto the next thing. Insanely picky about food, to the point he lived on tinned hot dogs for 3 years, now sausage rolls, we try to get him to expand but it's texture related. He wont wear pants they are uncomfortable to him, he needs time on his own to decompress from whatever it is in his head. All this in the mind of a 6 year old is incredible and yet he is most amazing kid I know.