Hendricks, a forerunner of the Fluxus movement in the 1960s, recalled meeting Buczak, a fellow artist, two years before, at a Libra party hosted by the musician Phill Niblock. “I think Brian was the only other queer person there, and we spent a lot of time dancing together. Later, out of the corner of my eye I saw him leaving with his friends. There’d been this kind of electricity between us while we were dancing so I went running after him down Lafayette Street. They were heading down to Lower Manhattan — to the Ocean Club or one of the places that were the in places to go to at that point. I caught up with him and I said, ‘Hey, I don’t even have your phone number.’ So I went along with him and it ended up that Brian came back here with me. I had just moved into this place, and my bed was a mattress on a pile of lumber up in the attic and, well, that’s where we went together, through the night, into the early hours of the morning and it was the beginning of a wonderful relationship.”

At that time, Hendricks was already a fixture of the New York art scene. The legendary Happenings he organized with his Rutgers University colleagues (including Allan Kaprow, George Brecht, Bob Watts and Robert Whitman) at the University and at the Cafe Au Go Go (where Hendricks had done some performative work with his former wife, Bici) were transforming the landscape of contemporary art. Hendricks began painting the sky over his second home in Cape Breton, Nova Scotia. It quickly became a favorite and lasting subject. (He likes to call himself a “cloudsmith.”)

“I would say that the art world in the ’60s was a guy’s world,” said Hendricks, who witnessed Neel’s struggles firsthand. “As a woman, Neel was marginalized. It was an art world where abstraction was the answer in terms of art making. And she was a dogged realist. So she was being marginalized on two counts.” The trio officially sealed their friendship in 1978 at Rutgers, when Neel gave a lecture there. Hendricks and Buczak offered her a ride back into the city and when they arrived, she invited them up to for coffee. They sat in the kitchen and talked for hours. “She was a great story teller — just as in her portraits, she really gets in and extracts the essence of a person’s personality,” Hendricks said. The next morning they received a phone call from Neel’s daughter-in-law, who said, “Alice wants to paint you. Can you get up here by 4?” She told them to wear the same clothes they had had on the night before, and when they arrived at her studio at 103rd Street and Broadway, she asked them to sit just as they had been sitting at her kitchen table having coffee. “She had her canvas all ready and got to painting us.”

After their sitting, Neel referred to Hendricks and Buczak as the happy couple. “Alice often joked about that,” Hendricks said. “There’d be these heterosexual couples that she’d be painting in the midst of some sort of marital strife, and there always seemed to be this anger or tension or whatever that came through.” Even as Neel became a successful artist, the three stayed close. “She took us in as her children,” Hendricks said. “There’d be some party or reception and she’d call and say, ‘Come along with me.’ It’d be some penthouse apartment on Fifth Avenue, and we’d go and she would want to just sit with us and talk and not be treated like a celebrity.”

Buczak’s untimely death from AIDS in 1987 was a benchmark moment for Hendricks, who asked his friend Philip Glass to help him commemorate Buczak’s life. (Glass’s “String Quartet No. 4,” written for Buczak, played in the background as Hendricks and I spoke.) Last summer, at Hendricks’s 80th birthday, a small group came and performed the quartet for guests including Glass, Dennis Russell Davies and his two young sons, a moment Hendricks recalled as being magical.

Hendricks still lives in the West Village house he and Buczak shared for nine years, which he says is “full of Brian’s work and spirit.” And he still has the green sweater he wore that day in 1978. But when he and his current partner, the artist Sur Rodney (Sur), went to the opening of the Alice Neel show at David Zwirner, he didn’t dwell in the past. “The show is beautiful,” Hendricks said. “Sur and I were commenting on the quality of the white of the wall. It wasn’t just white, it was a white that worked with the paintings and the quality of the standardized frame where the stretched canvas was floating in this simple border. Each painting has room to breathe and to live and be itself.”