Kelly’s expletive-filled rant captures the spirit of this administration, at least as drawn by Sims. The book is filled with insights into some of the most defining elements of Trump’s White House, including the president’s strained relationships with former House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell, the rampant infighting, and the mechanics—such as they were—that underlay key policy decisions. The result is a cutting account of an administration steeped in turmoil from the outset.

That theme alone is unsurprising. It’s hardly newsworthy, for example, that the Trump-Ryan relationship was fraught. But Sims, in his up-close perch, vivifies the friction. He writes of the evening that Trump watched on television as the speaker criticized his remarks in the aftermath of the white-supremacist rally in Charlottesville, Virginia. From his private dining room off the Oval Office, “jaw clenched,” Trump yelled for his secretary to get Ryan on the phone. He then stood, clutching the remote control “like a pistol.” When his secretary gave him the go-ahead, Trump snatched up the phone.

“Paul, do you know why Democrats have been kicking your a— for decades?” his tirade began, as Sims tells it. “Because they know a little word called ‘loyalty.’ Why do you think Nancy [Pelosi] has held on this long? Have you seen her? She’s a disaster. Every time she opens her mouth another Republican gets elected. But they stick with her … Why can’t you be loyal to your president, Paul?”

His voice grew louder. “You know what else I remember? I remember being in Wisconsin and your own people were booing you. You were out there dying like a dog, Paul. Like a dog! And what’d I do? I saved your a—.” (A spokeswoman for the former speaker declined to comment.)

It was a stunning scene, the president verbally shredding the speaker of the House, a member of his own party. And all the while, Sims was listening from the entryway, the improbable wallflower of the West Wing.

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In likely no other administration would such an obscure staffer see all that Cliff Sims did. But as Sims told me in a series of interviews, “I just wasn’t gonna move to Washington and work in this White House without trying to put myself in the middle of everything.”

That kind of ambition is common in D.C. newcomers, but Sims benefited from a White House whose norm-shattering first year included few limits on who could hang around the Oval Office. Sims just happened to take full advantage.

Sims, then 32 years old, was brought into the White House after his successful run coordinating messaging on the campaign. There, he learned many of Trump’s quirks: how he preferred filming against dark backdrops because he didn’t like the way his hair looked against white ones. How it was best to always have a travel-size bottle of Tresemmé Tres Two hair spray on hand, just in case. And, perhaps most important, how Trump craved “normal” conversation. “I always tried to interact with him like a normal person,” Sims told me. “In between whatever work we were doing, I would look for opportunities to talk about what was in the news, or tell him about the latest gossip from entertainment or politics, or whatever.”