I babysit for my 3.5 y.o. grandson who is PDD-NOS. He is in a continuting program but language is very delayed. It is very difficult to get him to interact with me. He prefers to stim. So, I will engage myself in various activities (drawing, playing with blocks, puzzles) hoping to draw some interest from him. He will, each time, approach me only to ruin, with a laugh, every thing I am doing. If I build a tower and try to hand him a block, he throws it and knocks tower down. If I draw on the blackboard, he erases. If I play with pegs, he sends them flying. I cannot re-direct with any success. How to turn negative behavior around?