One of the greatest roles that Robin Williams hoped — but never got the chance — to play is coming back around, with a new edition of First Person Plural: My Life as a Multiple, Cameron West’s memoir co-written with wife Rikki West, hitting shelves May 26. The original 1999 book offered an intimate window into West’s experience living with dissociative identity disorder, formerly known as multiple personality disorder, as his dozens of alters developed out of severe childhood trauma.

West, now a Ph.D. in psychology, struck a chord throughout the world by unflinchingly telling his story. He went on The Oprah Winfrey Show, reached instant New York Times best-seller status — and sold the screen rights to Disney in a seven-figure deal with Williams attached to star and Eric Roth slated to write an adaptation.

The combo could hardly have been more pedigreed: Williams was a year out from his Oscar win for Good Will Hunting, while Roth was newly nominated for his The Insider screenplay (he’d also won an Oscar a few years earlier for writing Forrest Gump). Roth dined with West in preparation, snagging a table upstairs at Mr Chow in Beverly Hills, but they didn’t get into the script’s nuts and bolts. “I don’t remember him asking me any particular questions,” West says now. “He was just using the book.”

Williams, though, had endless questions. The Wests were invited to the star’s house to discuss the project, and a quick bond was formed. “He’s a lot more like you than you think,” West recalls Williams’ wife at the time, producer Marsha Garces, telling him. “He has a lot of wounds in his mind.”

Williams sat so close to West that they were touching; the actor intended to understand the man he was about to take on. “He wanted to meet my alters,” West says. And so he did — after which Williams “had me rub his arms,” West says. “He said, ‘You can see the hair on my arms sticking up.’”

Williams had two dogs at the time and was curious to see how they’d react. “Dogs are incredibly perceptive, and when alters come out, they know — so they know it’s not you. They react to different alters completely differently,” West says. “Anybody who’s ever seen that in the room says, ‘Oh my God,’ and that was Robin. He said, ‘Holy shit. Look what my dog just did.’ ”

The pair stayed in contact until a few years before Williams’ death in 2014. A deep, almost unspoken understanding developed between them that they continued to explore in advance of the assumed movie-to-be. “We got as close as you could get in that way because this was a person with endless amounts of fame and endless amounts of money,” West explains.

Roth, meanwhile, had been talking up his screenplay at Vanity Fair’s 2000 Oscars bash, per a New York party report, while Winfrey hyped the forthcoming film on her show. But because of leadership changes at Disney, the project lost its champions and momentum stalled, even though, a source familiar with the deal at the time says, Williams’ attachment was indefinite “with a turnaround clause that would have likely been built into his Disney producing deal.” Says West: “It seemed like it was lined up to be a really big thing, and they paid a lot of money for it. That was a heartbreak for us.” He and Rikki still have a draft of Roth’s screenplay tucked away in their home. The rights remain with Disney.

In popular culture, DID is still a widely misunderstood and rarely portrayed condition despite a recent study finding that it affects tens of millions of people worldwide. First Person Plural stunned readers for that very reason, offering a far more complex portrait than the most famous depictions to that point, like the Sally Field-led Sybil. More recent projects, like United States of Tara and Moon Knight, have factored in advancements in understandings of the disorder — as does the new edition of First Person Plural, which incorporates more of West’s own life.

In that way, it still stands apart. “I had four more hospitalizations, more alters came out,” West says of the period since the book’s initial publication. His relationship with Rikki remains the anchor: “It’s a love story. We faced a serious challenge that we did not know we could overcome.” As the book nears its rerelease, he’s hoping the screen project can be revived in Williams’ memory, now in a scope befitting a series: “There’s so much more to tell. There’s now a whole lifetime.”

This story appeared in the May 6 issue of The Hollywood Reporter magazine. Click here to subscribe.