When pressed for a one-word assessment of the new U.S. president, this is what two of Donald Trump's biographers came up with.

"Ego," said Tim O'Brien.

"Needy," said Michael D'Antonio.

Both authors have spent a lot of time with the real estate mogul who now sits in the Oval Office, trying to chisel away at what D'Antonio describes as a self-created caricature to get at the man behind the public persona.

"The main thing that drives Donald Trump is the pursuit of fame, and as an ancillary to that, popularity," said D'Antonio, a Pulitzer Prize winner and the author of the 2015 Trump bio Never Enough.

O'Brien agrees that fame is a strong motivator for Trump.

"He has a very cinematic sense of himself. He's fascinated by celebrity and films," said O'Brien, who wrote TrumpNation: The Art of Being the Donald. O'Brien said that Trump's need for attention is coupled with insecurities about his intellectual prowess, his wealth and his attractiveness to women.

"I think because of some of his insecurities, he has a constant need to dominate people, whether it's business partners, political opponents or the media — almost anyone who he feels crosses his path," said O'Brien.

'I think for the sake of the country and the world, an evolved Donald Trump who takes the dignity and the legacy and the responsibilities of the Oval Office seriously is in everyone's interest,' said one of Trump's biographers, Tim O'Brien.

Both writers say Trump's colourful past paints a broad-stroke picture of the type of leader he could be.

"Donald Trump's past, which is marked by excess and extreme statements, and even a willingness to go bankrupt many times over, suggests to me that his presidency will be of the same style," said D'Antonio.

Social media attacks

O'Brien said that Trump's social media use at times reflects his insecurities, particularly his need to attack those who criticize him, from the press to Congressman John Lewis, who called Trump's presidency "illegitimate."

"It really raises questions about whether or not he can separate his own emotional insecurity and emotional needs from good policymaking, good national security positions and generally good, judicious behaviour."

Tim O'Brien, author of TrumpNation, The Art of Being the Donald, says Trump's past shows he's a man with a short attention span who likes to dip in and out of issues and not engage in the complexity of things. (Steven D'Souza CBC News) O'Brien says Trump's short attention span will also influence how he governs.

"His past would suggest he's someone that enjoys dipping in and out of issues, but not necessarily seeing things through to their conclusion or engaging with the complexity of things," O'Brien said. "I think what we can expect from him is someone who responds quickly and emotionally, but often not strategically."

D'Antonio said Trump's tendency to be more instinctive than analytical could pose problems. It comes from the lessons instilled by his father, who taught him to be a "killer" and a "king."

"He could overreact in a moment of crisis — order a military strike, order one against the wrong target," said D'Antonio. "Sometimes the best action is no action, and I'm not sure he recognizes that."

After O'Brien published TrumpNation in 2005, Trump became so enraged by O'Brien's valuation of his net worth that he launched a $5-billion US lawsuit. While the suit was eventually thrown out, as part of the lawsuit, O'Brien saw Trump's tax returns, though he's legally prevented from speaking about it.

O'Brien said while Trump has survived real estate crashes and bankruptcies, he's always done it on his own terms.

"I don't think Donald Trump has changed since he was about seven years old. I think Donald Trump is essentially a seven-year-old grown old," O'Brien said.

No longer the boss

D'Antonio said it's possible Trump may change his behaviour somewhat because he finds himself in a new environment.

Trump has a love-hate relationship with the media, say his biographers. (Don Emmert/AFP/Getty Images) "At age 70, he is for the first time working for someone else. For his entire adult life, he's been the boss. Now, as he takes office, he is responsible to someone else — in this case, the American people — for the first time ever."

D'Antonio said Trump will struggle at first to work with others, not recognizing that there are many in Washington who have their own power base and can challenge him. If Trump can adapt, he could rally others to his cause.

"If he fails at learning how to be a politician and act in good faith with others, then we're going to have four years of crisis," D'Antonio said. "He could even be impeached."

Both authors say that Trump's need to be popular, and a fear of humiliation, could motivate him to change his mind on certain issues.

"I think the desire to avoid that shame is going to drive him towards perhaps more moderate policies. So we might prefer that Donald be afraid of humiliation, because it means he'll want to succeed," D'Antonio said. "He wants Americans to love him."

The author says Trump's greatest strength is also his greatest weakness: his self-confidence. And while there's no challenge that frightens him, D'Antonio says Trump still must listen to those around him. "There's no amount of self-confidence that is going to steer history, even if you're president of the United States."

O'Brien says Trump's greatest strength is that he's a survivor, both in business and now in his brief political career. But he doesn't think Trump has any interest in evolving. He calls Trump "wildly ignorant" on public policy and emotionally and intellectually undisciplined.

"He's not like any other president who has preceded him into the White House. He is ill-prepared — in many ways, he's ill-suited for the role," O'Brien said.

Love-hate relationship with media

One aspect of Trump they think probably won't change: his love-hate relationship with the media.

"He only likes the media when the media is flattering," O'Brien said, but adds that no one is in Trump's doghouse for very long.

Trump biographer Michael D'Antonio says one of the biggest adjustments Trump will have to make as president is understanding he's no longer the absolute boss but actually accountable to the U.S. people. (Steven D'Souza/CBC News)

So what kind of president does Trump want to be?

"I think Donald Trump wants to be a president who is regarded as authoritative, decisive and as strong as perhaps [General George S.] Patton was in the films about World War II," said D'Antonio.

O'Brien, on the other hand, doesn't think that Trump has a firm idea.

"I don't think he ever thought about what kind of president he wanted to be. I don't think he thought through what four years of sitting in the most powerful office in the world would be like," O'Brien said.

Both writers maintain some optimism when considering what kind of president Trump will be.

"He can be bellowing, he can be bullying, but he also can change in his mind and he's done it many times," said D'Antonio. "So if he can tap into that part of himself that is a survivor and is adaptable, we'll be entertained by his behavior but we may also be benefiting from his leadership."

"I think for the sake of the country and the world, an evolved Donald Trump who takes the dignity and the legacy and the responsibilities of the Oval Office seriously is in everyone's interest," said O'Brien.

"Having spent quite a bit of time with him, and having covered him for a very long time, I don't expect any of that kind of evolution to happen. But let's wait and see."