Even when physically present, Huberman can be hard to track. “I don’t have total fidelity to who Andrew is,” says his friend Patrick Dossett. “There’s always a little unknown there.” He describes Andrew as an “amazing thought partner” with “almost total recall,” such a memory that one feels the need to watch what one says; a stray comment could surface three years later. And yet, at other times, “you’re like, All right, I’m saying words and he’s nodding or he is responding, but I can tell something I said sent him down a path that he’s continuing to have internal dialogue about, and I need to wait for him to come back.”

When they fought, it was, she says, typically because Andrew would fixate on her past choices: the men she had been with before him, the two children she had had with another man.

Another friend found him stressful to be around. “I try to be open-minded,” she said of the relationship. “I don’t want to be the most negative, nonsupportive friend just because of my personal observations and disgust over somebody.” When they were together, he was buzzing, anxious. “He’s like, ‘Oh, my dog needs his blanket this way.’ And I’m like, ‘Your dog is just laying there and super-cozy. Why are you being weird about the blanket?’”