He would arrive with a bag of fresh pastries and some new toy, and he would set his briefcase down by the door and drop straight to his knees on the play mat, this man who had spent decades on his feet in boardrooms, and give himself over entirely to the serious business of playing with his niece.

He handed her a plush golden retriever one Saturday and she squealed and clapped her chubby hands, and I watched my formidable brother melt into a puddle on my living-room floor, and I thought that I had never seen him so happy, or so much himself, in all the years I had known him.

He was the devoted uncle now, and I was the father, and between us we ran the whole enterprise of Maya’s days: the routines, the meals, the therapy schedules, the early-education games, the thousand small acts of a life being carefully and joyfully built.

“She turned the pages of a book yesterday,” I told him one morning, handing him a mug of black coffee as he knelt on the mat.