If you displayed a neutral appearance (no overt body language, you were quiet and kept to yourself, avoided eye contact, etcetera), you'll provide a less threatening appearance, which will allow the individual who is frightened to step outside his or her shell to attempt to interact with you (as the world is so overwhelming). Higher-functioning individuals tend to do this (children with AS included).
This same appearance can offer the aloof individual an interesting axiom for him or her, as you act different to most people, and he or she may just notice you. Lower-functioning individuals tend to be oblivious to many things except their "repetitive behaviours", but certain things/people may engage them.
I've been both, and even though I can't remember the aloof years, I have words from my mother.