Their relationship was complex. In a 2021 biography of MacGowan, O’Connor recalled performing a version of “Haunted” with him while he was using heroin. “The producers were freaking out because Shane was nodding out on smack in between the verses,” she told MacGowan’s biographer, Richard Balls. “I was singing my verse and they didn’t believe he was going to wake up and neither did I.” In 1999, a few years after that collaboration, O’Connor called the police on MacGowan when she found him using heroin at his home.

They fell out over it, then grew back together. Later, when asked if O’Connor’s police call ended his relationship with her, he replied, “No, but it ended my relationship with heroin.” In 2004, when O’Connor gave birth to a baby boy, she named him Shane. And at MacGowan’s 60th birthday party, in 2018, she performed the song “You’re The One,” which MacGowan originally sang with Moya Brennan.

O’Connor and MacGowan first encountered each other in the 1980s in London, MacGowan told me over email in 2021, though he did not remember the exact circumstances. What he recalled was their dynamic. “She was very shy and I was speeding, so I talked a lot,” he said. Hanging around with him and Joey Cashman, his Pogues bandmate, “must have been a nightmare for her,” he said. “I talk a lot, but Joey makes me look like an introvert.”

In her 2021 memoir “Rememberings,” O’Connor did not write much about MacGowan, but she did make a little joke about him and speed. She experimented with the drug, she said, during a stay at St. Patrick’s psychiatric hospital in Dublin. “In the locked ward where they put you if you’re suicidal, there’s more class A drugs than in Shane MacGowan’s dressing room,” she wrote.

Their collaborations highlighted the distinctiveness of their voices — his gruff, hers incandescent. But when I interviewed the singer-songwriter Bob Geldof about O’Connor, he found an aesthetic similarity between them. He appreciated that they were among the few singers who did not sound blandly American. “She has an Irishness to her voice,” Geldof said of O’Connor. “Bono doesn’t sound Irish. Shane MacGowan sounds Irish.” In our interview, MacGowan called O’Connor “a brilliant singer and a brilliant Irish singer, one of the best.”