"Koontz writes terrifying stories of murder and mayhem, yet is incapable of watching a gory movie. He hasn’t flown for 50 years..."

"... after a flight he was on encountered serious turbulence and a nun on board proclaimed, 'We’re all going to die.'... Mostly, Koontz stays put in Orange County. Easier, safer. He installed a towering fence, which partially obstructs the view, to protect his golden retriever Elsa from rattlesnakes. His 12,000-square-foot art-filled manse features the latest innovations to guard against wildfires....  'When the writing is working, nothing stops me,' he says. He worked 36 hours straight — twice.... Koontz... doesn’t read emails... and won’t open a browser, even to check facts or the news. 'I never go online. Never. I don’t trust myself,' he says. 'I know I’m a potential obsessive, and I don’t want to waste time.' Head down, nose to keyboard.... He starts with characters.... 'Life Expectancy'... opens with a deranged, chain-smoking, aerialist-abhorring menacing clown named Beezo in a 1970s maternity waiting room. 'I give the characters free will,' he says. 'The novel becomes organic and unpredictable and much more interesting to me.'"

 
From "What scares master of suspense Dean Koontz? Plenty. He’s sold more than 500 million books, writes two novels every year, lives like a prince and keeps his manuscripts in the fridge in case of fire" (WaPo). 

And that's how you write: You're afraid of everything and you plant yourself firmly in one rattlesnake-proof place, you posit a handful of traits for a character — scary/odd things (like the abhorrence of aerialists) — then you dig in and write write write. Never stop.