MrStewart wrote:
I realize the intent of your question pertains to human companionship, however, when I read your thread title the first thing that came to mind was not humans at all. The first thing I thought of is cats. In terms of personality and social behaviour there is a lot of common ground there, between people on the autism spectrum and domestic cats, i mean. Or there is for me, anyway. I don't know about other autistic people.
My first thought was a dog. Great companions, unconditional love, always happy to see you and they expect nothing (except food) in return.