Determination and autism
One of the things you will notice with a child on the spectrum is the amount of determination they have to do something they want to do. The converse is also true.
Determination is something that can be used as a force for good or evil. Learning how to use it in a positive way is something people on the spectrum can find hard to accept. I think because they see things in black and white, just because they want it, this must be right and I will have it.
Part of dealing with it is giving them warning that this game/book/task/whatever it is….is going to have to stop after so many minutes, pages, turns, or whatever the thing they are determined about uses.
Achieving is great and determination CAN get you there, but NOT when the determination changes to frustration and anger. At that point the adult (whoever they are) needs to change the situation.
When you are on the spectrum and have got into that zone, it’s not easy to emerge from it without a breakdown of some sort. And whoever the caregiver is, they need to be prepared to deal with it.