One of the most fundamental negative experiences I link with Autism is the feeling and fear of evaporating. This is not to be confused with dying. The two are completely different. Imagine yourself being a field ofe bright sunny energy, no body, only energy. Now imagine this field evaporating swiftly. Like you simply ceased to exist. Vanished into air.
That’s the fear of evaporating.
I don’t know where it comes from, I can only say it’s fundamental for me.
These articles give more information about more common fears of autistic children:
19 fears and how to deal with them
Mini article about gender identity issues among autists
A far more scientific article. Beware, small printed. Use CTRL+[+] to zoom in.