He purses his lips and rolls his eyes cartoonishly, then nods his head and tilts it to the side, like a puppy. At times, he’ll grasp the side of the lectern with both hands and lean forward, and then back, seemingly out of boredom, or restlessness.

When he’s asked tough questions about his rhetoric, he blames political correctness and then deflects, talking about the sad state of the country. When he’s challenged to explain his more outlandish views, he says he should just get credit for the fact that anyone cares about the topic. He is rude and defiant, talking over anyone who dares needle him, even telling them to “be quiet.”

She is a more diplomatic but no less towering presence. She opens and closes her hands as she speaks to put fine points on her statements. She nods her head slowly when she’s asked a question, the corner of her lips upturned in a not-quite smile that conveys a sort of polite aggravation with the entire process. When an opponent criticizes her, her eyes narrow, and the not-quite smile morphs into a glare.

She’s a master at answering the question she wants to answer, rather than what’s originally asked. Moderators sometimes have to push, twice, even three times, to get an answer that pertains to their query.

This is Donald Trump and Hillary Clinton on the debate stage this past primary season. On Monday night, at Hofstra University in Hempstead, New York, the former friends will meet onstage for the first time as their respective party nominees, following months of arguing with and mocking one another from afar.

An extensive review of all 21 primary debates, conducted by The Daily Beast, provides insight into what we can expect on Monday evening, when two of the country’s most disliked and divisive politicians spar in person for the first time.

Their styles couldn’t be more different, but to their detractors, they share a common flaw: a tendency to flout the facts. The degree to which this is true varies greatly for each candidate—a Politico investigation recently found that, in a week’s time, Clinton lied a third as much as Trump did—but for the public, such distinctions may not come into focus until the candidates are sparring one-on-one, their strengths and weaknesses on display for 90 minutes and with no commercial breaks.

Clinton has a reputation as a skilled debater, someone with a deep and nuanced understanding of even the most complex policy issues, so deft that she managed to frustrate a young Senator Barack Obama during the 2008 Democratic primary (although not enough to win).

Trump proved adequate in this context and capable of sucking up the oxygen in the room—many questions posed to his Republican rivals had to do with him—but his campaign is aware that it’s not where he thrives, and has worked to set expectations low for his performance. Monday night will be the first time in his short political career that he has ever debated an adversary one-on-one.

For all their differences, Clinton and Trump each have the distinction of having been famous for decades—Trump since the 1980s and Clinton since her husband, Bill, first ran for president in 1992—meaning there are a wide array of events, statements and changes of the heart about which they can and likely will be asked. In the primary debates, certain questions were asked repeatedly.

There were 12 Republican primary debates in total, the first of which, in Cleveland in August of 2015, included all 16 candidates: Trump, Jeb Bush, Marco Rubio, Ted Cruz, Chris Christie, Rand Paul, Carly Fiorina, Ben Carson, John Kasich, Rick Perry, Scott Walker, Rick Santorum, Mike Huckabee, Lindsey Graham, Bobby Jindal and Jim Gilmore. That debate, and the six that came after it, was split into two parts—a so-called “undercard” debate for the candidates with lower poll numbers, and then the main event, for the top-tier.

On the other side, there were a mere nine debates, and far fewer candidates. While the primary began with a five-way race (remember former Rhode Island governor Lincoln Chafee? How about former Senator Jim Webb? He killed a guy!), it quickly dropped to three. Former Maryland governor Martin O’Malley left the race after he lost Iowa, back in February, narrowing the field to just two candidates: Clinton and Bernie Sanders, the Independent senator from Vermont.

Despite Sanders’ surprising challenge, Clinton was always going to be Democratic nominee, so moderators hit her with hard questions from the very beginning.

But two topics that came up nearly every debate, and likely will Monday night as well, were Clinton’s role in Libya and, of course, her use of a private server for her emails and the FBI investigation that while over, continues to dog her campaign.

Her reactions and answers to those two topics show a contrast between a topic Clinton wants to defend, and one she’d rather not talk about ever again.

When asked about her support for overthrowing Libyan dictator Muammar Gaddafi as well as the death of four Americans in Benghazi, Clinton’s answers was firm, calm and consistent.

In each debate, she outlined the situation on the ground and explained, point by point, why she made the decisions she did in the war-torn country.

On the emails, well, her answers varied from dismissive, to remorseful, to defensive, to downright exasperated.

At the second debate in November 2015—after the first debate when Bernie Sanders famously said he didn’t care about her “damn emails”—she laughed the issue off when asked about whether Democrats should be worried about “the other shoe dropping” as the FBI investigation continued. She had recently completed a grueling 11-hour interview with the House Benghazi Committee to rave reviews and it was clear she was feeling confident and completely in the right.

“Well, I think after eleven hours that's pretty clear. Yeah,” she answered.

At the fifth debate in February, she again dismissed it as a Republican political ploy—a callback to the “rightwing conspiracy” of the nineties.

“You know, before it was emails, it was Benghazi, and the Republicans were stirring up so much controversy about that,” she said. “And I testified for 11 hours, answered their questions. They basically said, ‘Yeah, didn’t get her. We tried.’ That was all a political ploy.”

But by March 2016, she used a more rehearsed answer: she “did not send or receive any emails marked classified at the time.”

At the end of a defiant explanation she concluded by saying, “I am not concerned about it. I am not worried about it and no Democrat or American should be either.”

The issue, of course, has not gone away, meaning the chances she will have to answer for it again Monday night are high.

During the Republican debates, moderators asked Trump often, in various ways, about his plan to build a wall at the U.S.-Mexico border and have Mexico pay for it. They asked, too, about trade, and his contention that “disastrous” trade deals took jobs away from America—and about his own hiring of foreign workers, despite his anti-outsourcing rhetoric.

His answers tended to come back to the same core ideas: America is no longer great but he’ll fix it, the military will get bigger despite the deficit getting smaller under his stewardship, he’s winning in the polls so that means he’s necessarily right about everything, and all of his policies will work in the end because he says they will.

For the other candidates, the repetition seemed to become an annoyance.

“He says five things!” Rubio said of Trump during a February CNN debate. “Everyone’s dumb, he’s gonna make America great again, we’re gonna win, win, win, he’s winning in the polls, and the lines around the states!”

In response, Trump pursed his lips so dramatically he looked like he was doing a Robert DeNiro impersonation.

“It’s true,” he said. “I tell the truth, I tell the truth.”

Rubio was not far off.

“If you look at the polls and if you look at the millions of people that have been pouring into the polls, it's, again, the biggest story,” Trump said in response to a question about his past as a supporter of Democrats and their ideas during a CNN debate in March.

“I beat Hillary, and I will give you the list, I beat Hillary in many of the polls that have been taken. And each week, I get better and better. And believe me, I haven't even started on her yet,” he said during that same debate.

During a Fox debate in March, he said, “I beat Hillary Clinton in many polls...Every single poll when it comes to ISIS and the military and the border say, by far, Trump is the best.”

Of the many open questions that will be answered in less than 24 hours is which version of these candidates will show up.

Will it be Stern Hillary versus Crazy Donald? Or perhaps Defensive Hillary versus Reasonable Donald?

One thing is virtually certain, no matter who shows up behind the lecterns: these two complex, driven, disliked, flawed candidates are in a dead heat.

After Monday night, it seems unlikely that will still be the case.