The basics of Autism are that some part (or parts) of the brain under-develop, and some other part (or parts) of the brain over-develop. (Brain scans have shown this consistently.) There are some fairly typical symptoms, but not every autistic person will have those symptoms. I, for example, have no real difficulty with making eye contact, a fairly common issue for autistic people. I'm neuro-atypical in different ways.
Dictionary-dot-com defines autism spectrum disorder as "any of various disorders, as autism and Asperger syndrome, commonly manifesting in early childhood and characterized by impaired social or communication skills, repetitive behaviors, or a restricted range of interests." I didn't manifest in childhood, not strongly enough to attract attention, anyway. Or not the kind of attention that got me tested and treated or anything.
I do have some of those symptoms. I've never really socialized well, and the older I get, the worse that gets. I tend to dislike change in my personal world (but not enough to be a republican, ha-ha!), and I have long preferred to communicate in writing over verbalization, at least when something was emotionally important to me, because I do so much, much better than I do verbally.
But, in the end, it all comes down to this: I don't think like you do.
That's hard to really wrap your head around, and, believe it or not, I get that-- because I have to constantly remind myself that very few people remember things like I do. This was pointed out to me a few years ago, when a friend mentioned some things we'd done when we were young and dumb, then said, "I'll bet you thought I forgot all that, didn't you?" When he seemed puzzled by me answering "of course not," we started talking about memory... and I came to understand that it wasn't just him that had a memory that wasn't as good as mine, it was most everyone. (Only my best friend comes close to having a memory that works like mine, and as well as mine, and [I think] better than mine on some subjects.) (Well, him and my gaming buddy R, whose memory is... actually kind of scary-good, even next to mine.)
I remember everything I've ever read that interested or amused me. Not verbatim, no, but by content. Hand me a book, I can tell you if I've read it or not without ever opening it, most of the time by title and author, though I sometimes have to check the back cover/inside flap copy.
I see mystery's solutions, often long before anyone thinks I should be able to, and I'm right about my deductions an ever-increasing amount of the time. I spot the horribly subtle clues that are in the book/show/movie, and there's the solution, boom. (To be fair, I miss the obvious [in both entertainment and life] a ridiculous amount of the time. Goes back to that whole "different way of thinking" thing, I suspect.)
I think about a ridiculous number of things that you don't have to, most likely. I have to think about socializing, which can make things a bit... odd, at times, I suspect. I have to work not to think about problems, be they mine or those of people I'm close to. I am currently nearly constantly thinking about either my upcoming disability hearing, or one friend's losing their job and having to move back home, or another's potentially dangerous problems that are a mix of personal and potentially legal. I have to actually push those things aside to think about other things. Irksome, on occasion, but other times, that kind of focus can be really handy....
Thing I'm trying to get at, here, is that all of you are going to (if you haven't already) very probably lose your patience with me, someday. When that day comes, ask yourself... "is this because he's being an ass, or is it just that he's neuro-atypical?" Because there's at least a chance that the difference/rigidity of my thinking is at the root of the behavior that irked you in the first place.
Honestly, I'm very rarely a jerk on purpose, especially to the people who are likely to be reading this in the first place.
"Neuro-atypical." That sounds so much better than "autistic," don't you think?