How to handle obsession within autistic children?

It sounds like Asperger syndrome. There are no general delays in cognitive development or speech. Obsessive behavior is one of the main traits of those with Asperger syndrome. I can't remember, even vaguely, but my mother tells me the tantrums and disturbing violent behavior I had at age four. I was much worse than him. I wouldn't be diagnosed until age 13. I think I may have had co-existing problems like anxiety but never received a formal diagnosis. My child psychiatrist about two years ago suggested underlying anxiety. All I understand is that my surviving of those times is miraculous. My never being taken away is owed to an unconditional mother, who confidently feels to have been worse than any of her children. Anyway, intervening early is the golden key to overcome this.