Before we were strangers, and before we were best friends, Rosie and I were enemies. We hated each other with the instinctive, uncomplicated hatred of children. Supposedly I once tripped her at JCC day camp; supposedly she pushed me into the kiddie pool. Probably neither story was true.

But back then, Rosie and I had no shot at real enmity. Her dad worked at Scripps with my mom; her mom worked at Proctor & Gamble with my dad. We belonged to an eight-family circle of Cincinnati Jews who shared season tickets to the Bengals and Reds. We lived in the same school district, belonged to the same synagogue, played on the same sports teams. I could reject playdates and shun her in music class, but I couldn’t escape parental logistics. In first grade, Rosie and I both started once-a-week Hebrew school, and a carpool was instituted. Her parents drove there, mine drove back.

One afternoon, after we got into her mom’s car outside our elementary school, she produced a corn-yellow plastic alligator from her backpack and told me he needed a name. I remember that naming the gator—we went with Jaws—took the whole ride, and that we arrived at Adath Israel wobbly and hot-cheeked with laughter. I remember telling Lia Kirschenbaum, my usual deskmate, that I wanted to sit with Rosie that day, which became every day. Rosie and I quickly moved into a world of our own invention. We made up elaborate games and stories, schemed all kinds of pranks we’d never play. We created a fused self we called Rochelle Birnbaum-Levitt—a decent mix of our names, Rosie Birnbaum and Michaella Connell-Levitt, and, looking back, a nice way of eliding the fact that I’m only half Jewish.

As we got older, we both came to understand that while our families might have made many of the same choices, they were hardly alike. The Birnbaums kept kosher; we didn’t. Her parents leaned right; mine, left. Neither of us got much adult attention, but for opposite reasons. Rosie had four little siblings, each more demanding than the next, while I had one brother, six years older and profoundly deaf, who my parents fussed over constantly.