I've worked with profoundly autistic kids and teens before. We're talking very low functioning, completely nonverbal types largely unable to care for themselves. They had to wear diapers and be hand-fed. They usually had extreme dyspraxia, and sometimes they had to wear helmets in case they feel down or ran into a wall head-first.
They would be highly dependant on routine, and for some, the ones that appeared to learn any skill at all for their teachers and caretakers, learned simply from routine and repetition. In many cases the kid did qualify to be considered "low intelligence" due to the amount of repetition it took for them to learn a skill. Others caught on a little faster, but none of these kids could be considered average intelligence.
The only other way of effectively communicating was through nonverbal yelling, screaming, spitting/throwing spit, biting, pushing, kicking, grabbing and running away. If you weren't very sympathetic, it'd be easy to see these kinds of autistics as "subhuman" or "animals."
However, I think these kids were often more aware than they were given credit, and did form bonds with the people they worked with. It may not have been the kind of bond formed between two higher functioning people, but I believe it was there and it was significant for that kid.