Christine McVie started out her time with Fleetwood Mac the same way the most of us did: as a fan. This was the late ’60s in England, when she was in blues-rock groups like Chicken Shack, who had some modest success with a charting version of Etta James’ “I’d Rather Go Blind,” featuring McVie on vocals. But drummer Mick Fleetwood’s blues-rock group was her favorite in the scene, and she would see them every chance she could. “I dearly remember the old days,” McVie told Cameron Crowe in a 1977 Rolling Stone story. “Fleetwood Mac had this one-of-a-kind charm. They were gregarious, charming and cheeky onstage. Very cheeky. … They had this tremendous, subtle power.”

Born Christine Perfect — “Teachers would say: ‘I hope you live up to your name, Christine,’ she quipped to the Guardian in 2016 — she would eventually marry Fleetwood Mac’s bassist, John McVie, and find herself enlisted to become an official member of the band in 1970. It’s a wholesome story: How often does someone go from superfan to in the band? But the humble origin of Christine McVie in Fleetwood Mac is particularly captivating when you consider the way that, in a couple of years, she would become a central, essential part of the very different Fleetwood Mac that took over the world.

McVie, who died on Wednesday “following a short illness,” according to her family, gave no initial musical indication that she wanted to write the arena-ready soft rock that she and the band would soon perfect. Her first solo album, 1970’s Christine Perfect, was more blues-tinged soft rock sans the arena, and her early contributions to Fleetwood Mac albums, like “Believe Me” on 1973’s Mystery To Me, were more Big Brother And The Holding Company than ABBA. That’s what makes her eventual work as the backbone of one of the most successful pop groups in history even more surprising. She seemingly picked up the ability to write a song like “Over My Head” just because that was what was on the agenda; just because she wanted to.

Fleetwood Mac’s history is so fractured that there are literally two self-titled albums and no one ever seems to question it. Listening to the 1968 Fleetwood Mac, when the group was led by Peter Green, and then jumping to the 1975 Fleetwood Mac, after Lindsey Buckingham and Stevie Nicks joined, it’s difficult not to view them simply as the work of entirely separate groups that just so happened to have the same killer rhythm section in John McVie and Mick Fleetwood. In truth, the most concrete musical bridge between the two sides of Fleetwood Mac is Christine herself, whose unmistakable voice — as deep and strong as a river in a storm — never changed much whether she was playing to 20 people or 20,000. (“I wonder if we enjoyed it slightly less playing in much bigger places,” she said to the Guardian just a few months ago. “Playing to thousands of people is more daunting, but you get used to it in the end. After the first 20 rows they all disappear anyway.”)

Perhaps the only other constant in the 50-plus-year history of Fleetwood Mac is a comical level of drama between the members, which shuffled in and out in an exceptionally convoluted manner. Well before Nicks and Buckingham showed up and immediately went through a breakup for the ages, the band was already a mess. First Peter Green had an acid-induced breakdown in 1970, then guitarist Jeremy Spencer had a mescaline-induced breakdown in 1971, then guitarist Danny Kirwan had an alcohol-induced breakdown in 1972. And in 1973, as a taste of the type of the absurdity that was to come, guitarist Bob Weston had an affair with Mick Fleetwood’s then-wife, Jenny Boyd (sister of Pattie Boyd), which led to the chain of events that created an opening for Nicks and Buckingham to bring their firework show of a relationship into the group.

Of course, Christine had a fundamental role in all the drama too, given that her marriage to John was falling apart around the time of 1977’s Rumours. (She wrote “Don’t Stop,” which hit #3 on the Hot 100, as an encouraging message for John, whose alcohol abuse had driven her away; “You Make Loving Fun,” which hit #9, is about the band’s lighting director, who she was surreptitiously involved with.) The Buckingham/Nicks/McVie/McVie love square fueled the band’s most iconic work, but from a distance, it seems clear that none of the members really viewed Christine as anything other than a peacemaker.

“When Christine is around the atmosphere is much better,” Nicks said in David Wild’s liner notes for the 2016 reissue of 1982’s Mirage. “Lindsey likes her a lot and recognizes her talent and doesn’t have any baggage with her. She’s sort of the Earth Mother who can speak truth to anybody. That’s always been her role. She’s not just a great voice — she’s the great voice of reason. She is able to make everyone come to their senses and get back to work.”

Still, this is Fleetwood Mac we’re talking about. McVie was no sinless angel — her recent example to The Guardian of how she and Nicks were “careful” was that they only spooned coke while the boys were doing it by the Heineken-cap-full — and she clearly relished some of the chaos along with everyone else on the planet who’s ever heard about it. In the 1977 Rolling Stone feature, Nicks warned that McVie is “very private, very much to herself,” but then Crowe got her talking about the band’s drama, and the difficult state of her relationship to John: “I still worry for him more than I would ever dare tell him,” Christine said, as if telling this to a reporter wasn’t the same as telling John herself. “I still have a lot of love for John. Let’s face it, as far as I’m concerned, it was him that stopped me loving him.” It appears that even Earth Mothers aren’t above mind games every once in a while.

But that was how she operated — subtly, precisely. Few would argue that McVie was the pure leader of the group, but when it was all said and done, she had more hits than Buckingham and Nicks (eight out of 16 of the tracks on the band’s 1988 Greatest Hits compilation were written or co-written by Christine, as noted in the New York Times’ obituary). In the liner notes for 1987’s Tango In The Night, Nicks is quoted as saying that the pairing of “Little Lies” and “Everywhere,” which went to #4 and #14 on the Hot 100, respectively, “just shows you that Christine is the hit songwriter in Fleetwood Mac.”

Christine Perfect was raised by a father who was a concert violinist and a mother who was a “healer,” which could not be a more appropriate origin story if you made it up. But it was her older brother who really had the most important impact on her trajectory. It was his sheet music of Fats Domino songs that Christine stumbled on at the family piano: “Because I could sight-read I started playing the boogie bass,” she told Mojo in 2017. “I got hooked on it, then I just got hooked on the blues. Even today, the songs I write use that left hand, it’s rooted in the blues.”

Despite being able to shift styles in an embrace of something saccharine enough to top the charts, you can almost always hear that Fats Domino spirit in her compositions. “Hold Me” is a true pop song, for instance — a tune so slippery in its seduction that holding on is no simple task — but when you focus on her piano part, it’s all boogie-woogie. It’s all sitting on the sheet music waiting at her family piano.

In the 2017 Mojo interview, McVie tells the story of how the beginning of her career in music was something of a stroke of fate. After getting a college degree in design, she was working as a window dresser at a department store in London; it was only when a friend recognized her in the window one day that she was asked if she was interested in joining Chicken Shack. “What would you say to shy window dresser Christine Perfect if you met her now?” asked the interviewer, Andrew Male, later on. Her answer: “I would say, ‘You’re Christine fucking McVie, and don’t you forget it!'”