The testimony of Fiona Hill and other developments in the impeachment inquiry against President Donald Trump are summoning a reckoning for a man accustomed to battling individuals and sometimes reality itself.

Trump is facing the prospect of his presidency collapsing under the weight of sworn testimony from principled public servants like Hill and, perhaps, appointees he used, abused, and assumed he had defeated. First among them is his former national security adviser John Bolton, a powerful personality who is also inclined toward combat.

A source has told CNN that Hill, Trump's former top Russia adviser, informed Congress on Monday that she saw "wrongdoing" in US policy toward Ukraine and that (as reported first by the Wall Street Journal) John Bolton had urged her to report troubling incidents to National Security Council lawyer John Eisenberg.

Hill's testimony may eventually be regarded as an inciting incident in a narrative that could be ranked alongside Watergate as a political tragedy caused by a single man's self-delusion. In the meantime, President Trump and the rest of us will endure not a drip-drip-drip of gradual revelations, it seems, but a torrent of scandal.

Along with Hill's testimony, another dam-breaker came late Monday with the New York Times report that Bolton, then National Security Adviser, was outraged by the efforts of Rudy Giuliani, Trump's personal lawyer, to recruit Ukraine into a plot to undermine Democratic Presidential hopeful Joe Biden.

"Giuliani's a hand grenade that's going to blow us all up," was how Bolton reportedly put it when he learned of the alleged scheme. According to the Times, Hill revealed Bolton's comment behind closed doors on Monday with the House intelligence committee, which is investigating Trump's alleged efforts to use foreign governments to "dig up dirt on his potential rival," Biden (something Trump has denied).

The Times also reported that Bolton associated White House chief of staff Mick Mulvaney and ambassador to the European Union Gordon Sondland with the plotting, according to Hill. And Hill reportedly told the committee that Bolton told her:"I'm not part of whatever drug deal Sondland and Mulvaney are cooking up."

Sondland has emerged as a key figure in the Ukraine scandal. It has been widely reported that he personally assured diplomat William Taylor that Trump was not seeking quid pro quo when he held up military aid slated for Kiev and then sought the "favor" of a Ukrainian investigation into the Bidens during his infamous discussion with Ukraine's new president.

More recently Sondland, who donated generously to Trump's inauguration, reportedly offered the reassurance not because he knew it to be true but because it was what the President told him. Sondland is also expected to tell the intelligence committee what he knows.

Trump has publicly acknowledged he would like both Ukraine and China to investigate the Biden family. He and Giuliani have repeatedly suggested wrongdoing by candidate Biden's son Hunter, who had served on corporate boards in both countries. There is no evidence of wrongdoing.

As self-destructive as Trump's public statements have been, they are made all the worse by his consistent alienation of those he has asked to serve in his government. From his original Secretary of State Rex Tillerson to his recently departed acting chief of homeland security Kevin McAleenan, Trump has made those around him miserable.

The chaotic quality of Trump's reign aligns with his well-documented record. A bullying and cruel boss, Trump has spent his entire life managing on the basis of caprice and intimidation. As I found while writing a biography of Trump, he made a habit of imposing awful demands of his underlings. Those who didn't quit accepted the exorbitant pay he offered along with rapid advancement as compensation for the stress and humiliations they endured.

When it comes to the perils of Trump's management style, Exhibit A is the case of his now-imprisoned lawyer Michael Cohen. Long the proud bulldog who advocated for Trump at every opportunity, Cohen's misplaced loyalty was one of the factors that led him to break the law during a scheme that involved making payoffs to a porn star and a Playboy model who claimed to have had affairs with Trump (which Trump denies). Cohen later flipped and became a star witness for prosecutors and Congressional committee.

As President, Trump has found himself in the position of needing experts and experienced hands who, as accomplished individuals with their own reputations to safeguard, were not so easily cowed. Unable to adapt, Trump has churned through top aides at a record pace.

Bolton, who became Trump's third national security adviser in as many years, accepted offers despite the warning signs. Bolton is himself a man with a reputation for bullheadedness -- but he is not widely regarded as corruptible. Indeed, his pugnacity and pride should have told Trump he would be an unlikely toady. Perhaps, as a purported supersalesman, the president thought he could win over Bolton.

With Hill's testimony, Bolton has been established as the kind of enemy Trump should fear. It's not hard to imagine that he too will testify about what he knows. How many others might follow?

Consider the record turnover in the upper reaches of the administration and you'll have some idea of what awaits the president and the nation. A Pandora's box full of Trump's enemies has been opened, and monsters he created are pouring out.