Harris began practicing BJJ in earnest in November 2011 and now trains three times a week, often in private sessions with Ryron Gracie, a head instructor at the Gracie Academy, which has locations in Beverly Hills and Torrance, California. Last year, he posted an essay on his Web site about his experience with BJJ, in which he rhapsodized about the pleasures of being nearly “choked out”—squeezed by the neck to the point of almost losing consciousness—or forced to cry uncle when a superior fighter cranks his head or limb in an unnatural direction. (BJJ teaches mercy: before you are maimed or killed, you “tap out,” typically by gently touching your opponent’s body to ask him to stop.) Harris likened training with an expert fighter to “falling into deep water without knowing how to swim.” He sees BJJ as a cycle of mock death and resurrection, wherein an expert may kill you many times per session. “To train in BJJ is to continually drown—or, rather, to be drowned, in sudden and ingenious ways—and to be taught, again and again, how to swim.”

Having read all this, I asked Harris to drown me. I am several inches taller and several pounds stockier than Harris, who is 5 foot 9 and weighs 165 pounds, and I am undefeated in single combat—though only because I have never been in a fight and flee anytime I see anyone who looks even vaguely threatening. Harris proposed that we meet for a private lesson with Ryron in Beverly Hills; he and Ryron would take turns drowning me.

When I arrived for our bout, I found Harris wearing a Gracie-branded T‑shirt and a gi (a martial-arts outfit) tied with a blue belt. Ryron, who turned out to be a pleasant guy and patient teacher, was my height, but leaner and more muscular, with close-cropped hair and nails. He started the lesson by asking me to lie on my back.

What followed was a sort of sorcery. Ryron straddled me, his hips pinning my torso to the floor, then invited me to try to wriggle out of this vulnerable position, from which he could freely punch my face without my being able to hit him back. I flipped to my stomach—a bad call, he pointed out, because now I couldn’t see him, while he could grab my head and bash it against the mat or torque my arm back. Instead, he suggested, why not put my left ankle here and my left arm there, pull this way, and roll like that? I complied, and within about a second I had flipped us both over: now he was on his back and I was straddling him. I repeated the move three times, never really sure how this recipe of foot and arm positions led so precisely to the flip.

I told Harris, who was warming up, that I could see how the cycle of helplessness and mastery might get addictive. “It’s the perfect schedule of reward for a lab rat,” he said. Next, it was Harris’s turn to attack me. He started off in a dominant position, although it was no longer clear to me what was truly dominant and what was just an invitation to be spun around and choked. He pinned me to the mat with his body. I pushed back, and when he raised his chest off mine for a second, I tried to exploit the opening by crossing an arm between us and prying him off me. But he had set a trap. When my arm crossed between our bodies, Harris sprang up and grabbed it, locking it across my throat. Ryron looked on, narrating the whole scene calmly, so unsurprised by my boneheaded errors that I wondered whether he could have described them with his eyes closed.