When Plimpton threw a party for Anywhere but Here in late 1986, Jobs flew to New York to accompany Mona to it.
They grew increasingly close, though their friendship had the complexities that might be expected,
considering who they were and how they had come together.
"Mona was not completely thrilled at first to have me in her life and have her mother so emotionally affectionate toward me," he later said.
"As we got to know each other, we became really good friends, and she is my family.
I don't know what I'd do without her. I can't imagine a better sister.
My adopted sister, Patty, and I were never close."
Mona likewise developed a deep affection for him, and at times could be very protective,
although she would later write an edgy novel about him, A Regular Guy, that described his quirks with discomforting accuracy.
One of the few things they would argue about was her clothes.
She dressed like a struggling novelist, and he would berate her for not wearing clothes that were "fetching enough."
At one point his comments so annoyed her that she wrote him a letter:
"I am a young writer, and this is my life, and I'm not trying to be a model anyway." He didn't answer.
But shortly after, a box arrived from the store of Issey Miyake,
the Japanese fashion designer whose stark and technology-influenced style made him one of Jobs's favorites.
"He'd gone shopping for me," she later said, "and he'd picked out great things, exactly my size, in flattering colors."
There was one pantsuit that he had particularly liked, and the shipment included three of them, all identical.
"I still remember those first suits I sent Mona," he said.
"They were linen pants and tops in a pale grayish green that looked beautiful with her reddish hair."