Few authors are precisely what devoted fans imagine them to be from reading their books, but rarely has the disconnect been more pronounced than it was with Kurt Vonnegut. His novels proclaim an easy-to-digest morality that pits simple human kindness against cosmic malevolence, flinging humorous defiance at an unjust world. Mother Night, Cat’s Cradle, God Bless You, Mr. Rosewater, and his masterpiece, Slaughterhouse-Five, captured the countercultural zeitgeist of the 1960s and have beguiled generations of young adults drawn to the writer’s self-described mission: “catch people before they become generals and senators and presidents … poison their minds with humanity.”

Humanity is not a word that springs readily to mind in association with Vonnegut after finishing Charles J. Shields’s empathetic but unsparing biography. Cruel, nasty, and scary are the adjectives commonly used to describe him by the friends, colleagues, and relatives Shields quotes. Vonnegut could be charming, but he was seldom kind; he frequently repaid loyalty with abandonment and betrayal. When Shields met the author in December 2006, he found “a lonely, disenchanted man” still angrily picking at childhood wounds.

Born in 1922, Vonnegut saw his wealthy family’s fortunes disintegrate following the 1929 stock market crash. He bitterly recalled his mother savagely branding her husband a failure, and he resented the preference he believed his parents displayed for older brother Bernard, a scientific prodigy. Vonnegut blamed Bernard for pressuring him to attend Cornell instead of taking the job he’d been offered at the Indianapolis Star newspaper. He did poorly in college and dropped out to enlist in the Army in 1943.

Shortly before he embarked for Europe, his mother committed suicide—while Vonnegut was home on leave, on Mother’s Day. As a POW in Germany, he retrieved the remains of residents smothered in their basements by the firestorm that engulfed Dresden after the Allied bombing. He saw starving fellow prisoners shot for stealing food. Thirteen years later, he watched his beloved sister die of breast cancer—the day after her husband drowned in a freakish train crash. Vonnegut may have nursed standard-issue youthful grievances far too long, but he also experienced real horrors that justified his fiction’s existential wariness.

So we’re inclined to cut him some slack as Shields’ narrative moves into the postwar years and we see Vonnegut browbeating wife Jane, whom he demanded to spend her life organizing his, and remaining aloof from their three children, just as he’d complained his parents did with him. He was under pressure, struggling to support his family as a fiction writer in the 1950s. His first two novels, Player Piano and The Sirens of Titan, sold poorly, and the few reviewers who noticed them were bemused by Vonnegut’s innovative blend of science fiction and satire. By 1965, heading to the University of Iowa to teach creative writing, he was “completely out of print and scared to death.”

Editor and publisher Seymour Lawrence turned things around for Vonnegut with a three-book, $75,000 contract in 1966. Lawrence also gathered the writer’s backlist—which by now included Mother Night, Cat’s Cradle, and God Bless You, Mr. Rosewater—and published it as a coherent body of work just as college students were discovering Vonnegut’s mordant irony and iconoclastic ethos. The stage was set for Slaughterhouse-Five to become a bestseller in 1969, and for Vonnegut to become a literary celebrity inclined to insert his own autobiography into increasingly mediocre novels that pleased only his indulgent admirers.

The disheartening downward march from Breakfast of Champions to Timequake (1997) was accompanied by a widening gap between the public and private Vonnegut. “Here was this clever, wise, witty person who could speak in front of an audience and be one of the most lovable people,” commented a friend of the writer’s nephew, adding “with those closest to him, it was a lot different.” His marriage was already terminal when photographer Jill Krementz entered the picture in 1970, but he tortured Jane with his ambivalence for nine years before they finally divorced. Shields’s quietly scathing portrait of Vonnegut’s second wife depicts Krementz as the social-climbing enabler of her husband’s desire “to be a famous New York City writer.”

The biography’s final third painfully depicts a man uneasily aware that his creative energies were fading, even as he cranked out more product. Asked in 2005 why he had just published a nonfiction book after declaring in 1997 that he was through with writing, Vonnegut replied wearily, “Well, I had hoped to be dead.” It took him 18 more months.

As was the case with Mockingbird, Shields’s bestselling biography of Harper Lee, And So It Goes is more notable for its intelligent analysis of personalities and capable understanding of the publishing process than for any brilliant insights about his subject’s work. People unfamiliar with Vonnegut’s novels are not likely to come away from this book with a burning desire to pick them up. Nonetheless, Shields’s sorrowful account of a writer who outlived his inspiration without ever outrunning his demons makes for compelling, if often grim, reading.