Paige had become serious overnight, packing lunches and reminding her sister to take a coat.

Chloe, younger and furious at the unfairness of the world, began telling jokes at precisely the moments when adults expected solemnity.

“I mistook it for being disrespectful,” he said.

“Sometimes I still regret the way I spoke to her.

She was frightened, and laughter was how she found her way through it.”

He described one terrible school conference.

A teacher complained that Chloe wouldn’t stop making light of difficult subjects.

Thomas had apologized for his daughter’s behavior, only to discover later that she was trying to cheer up a classmate whose father was hospitalized.