Obsession and compulsions are stereotypical labels for any interest a child with ASD. I had school friends who knew the capital city of every country in the world, who could list off the FA cup winners in England from the 1880s or who could recite an Oscar Wilde play and even more that collected football cards (it was the 80's). They didn't have ASD though. What is it, that defines an obsession with autistic and ADHD children?
My own son is into card battling games, Pokemon, YuGiOh and the like. He even had a small go at Match Attax but it waned after a few months (as a sports fan and old football card collector I was gutted😀). When he's caught up in his cards, he knows them all, strengths, weaknesses, types, combinations and will spend hours with them.
I know for some ASD children it's planes, trains, insects and whatever it is, that captures their interest. I discovered recently through an ASCEND program that children with ASD will focus on small details - this helps them get to grips with understanding the bigger picture of life, it helps them see connections and draw conclusions. They can use these conclusions then to relate to life, people and situations.
A child may focus on the car you drive (not just the make but model too) and draw from that the type of person you are. Many adults will do the same regarding Beamer drivers but the child does it so that they can possibly relate to you. To try to discover if you might get them. If you could fit within their circle.
This is the main difference, I feel, an ASD child will use their obsession to relate to their place in the world, within society, within the family and within school. It's their way of feeling comfortable. It's their way of feeling secure and safe. It's their attempt to create order.
As adults, it's our role to use these interests to help develop the child further. Asking questions, asking 'what if, then what, do you suppose' all with the intention of getting the child to think further. Trying to push the boundaries a little with each question to encourage them to open up their world a little each time.
Sometimes the interests will become compulsive and obsessive, this is where the adults really need to manage the child. Question and prompt their interests further than before, trying to bring the focus into everyday life 'what would happen if you met them at a playground? How do you think others would feel? What do you think the school principal would say if they arrived into class?' Or something along those lines. We want the children to feel safe and comfortable, so try no to be demeaning or confrontational. Use the small pieces of their jigsaw to bring them out a little bit into the world.
As smaller children I wouldn't be to adverse to using their interests to get the children to behave or focus on their next task. 'When you get up and are dressed, we can talk about X, Y or Z. When you finish your reading homework, we can talk about how X, Y or Z for 5 minutes (use a timer). When you have finished lunch we can watch X, Y or Z.' It's not blackmail, it's managing your child to get them to function. In our own case, our lad will want a screen for YouTube or to play a game. We have a rule where he doesn't get a screen until he's up and dressed. Otherwise, we know from painful experience, it's extremely difficult to get him moving. It took us around two weeks of being firm and committed, now, it's second nature to him. He's up, dressed and at the breakfast table before looking for a screen.
It's not always perfect. He's put jumpers on backwards. He's buttoned his shirt inside out (he hates buttons so much, he didn't notice any difference between buttoning normally vs buttoning his shirt inside out). I remember one morning he even had his trousers on and fastened backwards.
He still commits to getting it done though. Which is 80% of our battle in the morning.