But the more I watched Zac building the castle, the more I began to forget my physical discomfort. I hardly ever saw him play like this. He was so relaxed—not obsessive at all. In fact, after several unsuccessful attempts at a turret, he let the idea go. Do you know how huge that is? One of the characteristics of his autism is mentally getting stuck on something. He once talked about our new microwave for three full days. Every conversation was about the microwave: how it looked, how it sounded, where we should put it, what we should put in it. He had so many questions about it and the way it worked, I’d had to turn to Google for the answers to satisfy his insatiable curiosity. I like to think of it like this: his brain’s like a washing machine, and sometimes a thought gets stuck in the spin cycle. That’s the only way to describe it. Currently, he’s obsessed with snakes and the universe. Which means that he knows more about black holes and neurotoxic venom than most of the experts, which is kind of brilliant and amazing if you think about it.

After another half hour or so, Jake finally broke away from the two of them and crawled over to me. My body immediately stiffened, and once again, I was acutely aware of myself and all that work to get comfortable was gone in a puff of sand.

“Hey.” He sat next to me.

“Hey,” I replied, copying his tone because it just seemed so cool and smooth.

“They’re playing well together.”

“I know. I’m surprised. Playdates often end badly, especially if Zac becomes obsessed with doing something one way and the other person doesn’t want to.”

“Kids on the spectrum have a hard time reading other people’s emotions. It makes it hard to play with others.”

“How do you know he’s on the autism spectrum?” I knew I hadn’t told him this.

“It’s pretty obvious. To me, anyway.” He smiled.

“Of course. Yes! You coach them, the hula ball . . .” For some reason, I’d almost forgotten this part.

“Hoop ball,” he corrected with another small smile. “We’re trying to get it recognized as an official Olympic sport.”

“You are?”

Jake eyed me for a moment or two and then burst out laughing. “Joking.” He nudged me playfully on my arm and—