Trump always lashes out when he's cornered. He told me so years ago

President Trump's denials about former national security adviser Michael Flynn are raising new questions about obstruction of justice. Photo / AP

President Trump spent the early hours of Sunday the way he has so many mornings since he took office: watching Fox News and tweeting in ways that seem impulsive, unmoored from reality and potentially self-destructive. In less than two hours, he managed to criticise his own FBI; peddle a new conspiracy theory; attack James Comey, Hillary Clinton and ABC; and draw more attention to the Russia probe that has already implicated several of his aides.

As someone who spent hundreds of hours observing Trump so I could write The Art of the Deal, I find his increasingly extreme behaviour entirely consistent and predictable.

Former FBI Director and special counsel Robert Mueller. Photo / AP

Michael Flynn's guilty plea on Friday, and his promise to cooperate with special counsel Robert Mueller, brings the investigation closer than ever to the president's doorstep. For five decades now, Trump's pattern has been that the more aggrieved and vulnerable he feels, the more intensely he doubles down on the behaviours that have always worked for him in the past.

Sunday's tweetstorm won't be the last time the president indulges in self-pity, deceit and deflection. In all likelihood, it will get worse.

Trump's first move in the face of criticism has always been to assume the role of victim. "Unfair" has long been one of his favourite words. He always perceives himself as the victim, so he feels justified in lashing back at his perceived accusers. That's what he was doing in his blizzard of Sunday morning tweets.

Here's how he explained the tactic in The Art of the Deal:

"When people treat me badly or unfairly or try to take advantage of me, my attitude, all my life, has been to fight back very hard."

And this:

"Sometimes, part of making a deal is denigrating your competition."

Trump will also probably double down on lying even as he falsely accuses others of being dishonest. Consider his remarkable recent suggestion to aides that his crude remarks on the Access Hollywood tape about assaulting women might not be real - even though he has already publicly acknowledged that they were his, and apologised for them. Trump regularly rewrites his narrative, using what aide Kellyanne Conway has called "alternative facts," to fit whatever he wants to believe and convey in any given moment. This is classic "gaslighting" - a blend of lying, denial, insistence and intimidation designed to fuel uncertainty and doubt in others about what's actually true.

In the time I spent with Trump, I concluded that lying became second nature to him long ago, both because he lacked any conscience about being deceptive and because he discovered that he could get away with it. "Truthful hyperbole" is the sanitized term I gave lying in The Art of the Deal, with Trump's blessing. I have never met someone, before or since, who was untruthful so effortlessly.

In Trump's mind, he is only doing what's required to win. "Despite what people think, I'm not looking to be the bad guy when it isn't absolutely necessary," he describes himself in The Art of the Deal. Whether that's true, he plainly believes it has become necessary now. The more threatened Trump feels by troublesome facts, the more preposterous the lies he will tell.

When "winning" is your sole goal, the end always justifies the means, and that has given Trump an advantage throughout his career. To get the outcome he wants, he's willing to be scorned, parodied and even reviled in ways most of us are not. "I'm the first to admit," he said in The Art of the Deal, "that I am very competitive and that I'll do nearly anything within legal bounds to win." He is willing to flatter, cajole and seduce, or bully, threaten and humiliate, depending on which approach he thinks will work best. I watched him switch between these modes countless times during the 18 months I spent around him. If he was getting what he wanted from someone on a call, he'd invariably sign off with, "You're the greatest, you're the best." If he wasn't getting his way, he was equally comfortable hurling insults and making threats.

Will Trump stand by his son-in-law Jared Kushner as Mueller's investigation continues? Past form would suggest not. Photo / AP

Part of Trump's approach is to overwhelm the opposition by coming on like a human tsunami. In The Art of the Deal, this is the way he describes his six-year effort to build the New York City Convention Center on property he controlled: "In the end, we won by wearing everyone else down. We never gave up and the opposition began to melt away."

That's the same method behind the seeming madness of Trump's relentless attacks on such a wide range of people. Is it possible to imagine any previous president, for example, going after the father of a college basketball player, or a sitting judge? The more frequent and aggressive Trump's tweets become, the more threatened and vulnerable he is probably feeling. But he also knows that this approach can work. Even for some of Trump's most persistent critics, it's not easy to maintain the same sense of outrage when one unconscionable behaviour is quickly followed by another and another and another.

The other predictable pattern for Trump is his approach to loyalty. He expects it unconditionally - more so when his behaviours prompt backlash - but he provides it only as long as he gets unquestioning adulation in return.

Donald Trump with New York Mayor Ed Koch, and Roy Cohn at the Trump Tower opening in October 1983. Photo / Getty

One of the most revealing relationships in Trump's life was with Roy Cohn, best known as the chief counsel to Senator Joseph McCarthy, during McCarthy's pursuit of suspected communists. "Whatever else you could say about Roy, he was very tough. Sometimes I think that next to loyalty, toughness was the most important thing in the world to him," Trump said of Cohn in The Art of the Deal. For more than a decade, Cohn fought hard on Trump's behalf and was fiercely loyal to him. They often spoke multiple times in a day. But when Cohn became ill with AIDS in 1984, Trump dropped him immediately.

I interviewed Cohn for The Art of the Deal in 1986, shortly before his death. "How come Donald doesn't call me?" he asked me plaintively. In fact, Cohn knew the answer, which he had said to others: "Donald pisses ice water."

Tony Schwartz says, 'when all is said and done, [Trump] couldn't care less about anyone but himself'. Photo / AP

In times of stress, Trump focuses even more singularly on his own self-interest. I can't remember a single occasion during the time I spent around Trump when he seemed genuinely interested in the welfare of another human being, including any of his three then-young children. And at that time, he was under vastly less stress than he is now. If either Jared Kushner or Donald Trump Jr. become Mueller's next target, I can't help wondering what Trump will perceive as his self-interest.

To those who remain loyal to Trump, as he focuses on his survival as president, I suggest taking into account the one pattern that has been perhaps most consistent throughout his life: When all is said and done, he couldn't care less about anyone but himself.

• Schwartz is the chief executive officer of the Energy Project. He is also a business book author, professional speaker, and the ghostwriter and credited co-author of Trump: The Art of the Deal.