The screen door wheezed open. Kelli and Trevor were back, Kelli windswept and babbling as Trevor peeled the banana-­yellow jacket sleeves from her arms before she could get tangled up in them in her hurry to move into the next phase of her day.

Kelli had a charming way of being “done” with her home care friends at the end of their visits. She was unsentimental about goodbyes because Kelli was a creature of ritual, and she understood departures to be as essential to the visitation ritual as arrivals. After her baths, for example, she’d come charging out of the bathroom, trailing a flowery, girls’ locker room cloud of shampoo and conditioner, and head to her upholstered stool by the window, muttering Bye-bye now, bye-bye now without so much as a backward glance. “Oh, am I dismissed?” one woman had chuckled as she dried her hands and winked at me.

But Trevor had initiated a new ritual. And when I say new, I mean unprecedented. Before Kelli could charge up the stairs, Trevor inquired: “No hug for Trebie?”

Kelli does not hug. She has never hugged. She lets herself be hugged, certainly, although not for long. By way of physical demonstration, sometimes she used to put the back of her hand against my or my mother’s forehead, but this was a game from childhood. She’d say, “Mumma got a fever?” and my mother would obligingly lean over so Kelli could pretend to check. She was also good at shaking hands, one of those straightforward social rituals she wholeheartedly endorsed. But hugging, like eye contact, was never Kelli’s thing.

So I watched as Kelli hugged Trevor. As far as hugs went, it was definitively Kelli, meaning perfunctory, the way the back of the hand on the forehead was perfunctory — more of a performance of a fever-check than an actual fever-check. And this was more of a performance of a hug. She extended her arms straight out and kind of bopped them against Trevor’s upper arms as Trevor put his hands about her soft, expansive waist and gave it a squeeze.

Bye-bye now, bye-bye Trebie, said Kelli, charging up the stairs, past me, to get to her stool by the window.

There was nothing troubling about the hug except for the fact that it meant Trevor was special. And for some reason, I didn’t acknowledge that to him. I didn’t want to let Trevor know how extraordinary the chaste physical rite he’d initiated with my sister actually was. I came down the steps and took the jacket from him and signed the bottom of his clipboard, as I had learned that I was supposed to do from Kelli’s bathers.

“Same time next week,” said Trevor in an inflectionless way, so that, perhaps, the statement would come across as neither question nor instruction. It left a blank spot for me to fill in, I realized, like the blank spaces on the form I was signing.

“So,” I said. “I don’t know for how long.”