This becomes our pattern. Clay and Tamar are with her until they want to do something else, and then she’s mine. At which point I turn into a character in some kind of wacky operetta. I sing “ ‘A,’ You’re Adorable,” “Michael, Row the Boat Ashore,” and “Yes Sir! That’s My Baby,” Isabelle’s favorite. I know this because whenever I launch into it, her eyes roll back in her head like a Pentecostal catching a whiff of the Holy Spirit.

One of the best things about being a grandparent, I discover, is getting a free pass to act like an imbecile whenever you’re with the baby. And, as it turns out, I get to act this way a lot during our week away. Clay and Tamar take frequent walks and spend most evenings sitting out on the dock, talking. In fact, there’s quite a bit of talking going on. At one point I overhear them whispering about someone named Julie.

As far as I know, the only Julie they’re in touch with is the real estate agent who sold them their house. Lately, they’ve been complaining about the financial and practical pressures of maintaining it. What’s more, I’ve heard through the family grapevine that Tamar blames hormones for making her crazy in the early stages of pregnancy—crazy enough to want to leave Paris for Washington. And so I’m uneasy. I’m trying to unscramble the signals so that if and when my heart is broken, I am prepared.

I don’t have to wait very long. And I am not prepared at all.

A few days after we return home, Clay invites me to go for a walk. He seems nervous as we snake our way through the neighborhood.

“For the first time in my life, I feel responsible for your feelings,” he confesses after opening pleasantries.

“I’m so sorry, sweetheart.” I know how hard it must be for him to say this. “Please believe me when I tell you I’m sturdy and resilient. You are in no way responsible for my happiness.”

“That’s not how it feels.”

I try my best to reassure him. “You don’t have to take care of me,” I say, experiencing a wrench of the old grief—over the nasty divorce when Clay was two, over the endless tug-of-war that kept him shuttling back and forth between his father’s house and mine, over the succession of bad boyfriends who hijacked my attention when he was young. “I’m fine. Honestly.”

“It’s just that, well, you have a strong personality.” He pauses. “Plus, I never expected the grandmothers to be so involved.”

Another time, no doubt, I’d appreciate the irony. Me, a former wild child of the 1960s recast as a meddling grandma, like some awful character on a television sitcom. But now I feel like crying. Hollering too. If you didn’t want me to be so involved, why did you move here? Instead, I say, as neutrally as I can, “If I’ve intruded or overstepped my welcome, then I’m truly sorry.”

With Isabelle, everything is so simple: There’s nothing to do except love her. With her father and mother, however, I feel as if I’m crawling blindfolded up a steep ravine studded with land mines.

Clay and I walk along in silence for a while. He still seems anxious, so I know there’s more.

And then: “We’re going back to Paris.”

My body contracts as if a fist has just landed squarely in my chest. I miss Isabelle when I don’t see her for a few days. How will I manage when months go by? Who will I be to her? I’m afraid I already know the answer: an occasional confection, not daily sustenance; important theoretically, but in practice, nonessential personnel.

And then it hits me: I am nonessential personnel. If I died tomorrow, Isabelle would grow up fine without me. The early death of a parent may leave track marks on the soul, but unless a strong bond has formed, the absence of a grandmother is a loss more abstract than palpable. Which, in fact, is how nature, unsentimental in its practicality, seems to have designed it.

I am learning this lesson early, harshly. Now you see Isabelle, now you don’t.