(CNN) -- When Dr. Anthony Fauci returned to the White House briefing room on Thursday, he did so without the sour reality of a hostile president watching him from feet away in the Oval Office.
"I can tell you, I take no pleasure at all in being in a situation of contradicting the President," Fauci told the room, appearing nonetheless to take some pleasure in no longer having to dance around President Donald Trump's turbulent ego.
"The idea that you can get up here and talk about what you know, what the evidence, what the science is -- let the science speak," he added. "It is somewhat of a liberating feeling."
He demurred somewhat on his rocky history with the previous administration. But he made no attempt to veil his pleasure at the changing of guard.
For the 80-year-old infectious disease specialist, it was the latest act in a long history of serving seven US presidents. Fauci, who sat on Trump's coronavirus task force and endured Trump's public scorn, emerged to tout a new administration's plans and voice support for a new President's approach.
In some ways it was a turnabout. Though he was sidelined and ignored in the end, he still helped formulate a badly flawed Trump administration policy that failed to contain the virus.
But when things began to get bad, Trump's aides restricted how much Fauci could appear on television to offer warnings and disinvited him from briefing the President in the Oval Office.
Fauci and Trump disagreed on how to approach the pandemic, what the correct message was for the American people and how to balance reopening with preventing further contagion.
Through it all, Trump insisted he respected Fauci but disagreed with his approach. But at their relationship's nadir, Trump suggested he was considering firing Fauci. Attacks from Trump's allies led to death threats and enhanced security.
It was a different scene on Thursday. Fauci awoke before 4 a.m. ET to address the World Health Organization on the administration's behalf after Biden rejoined the body.
In the State Dining Room several hours later, Biden and Fauci greeted each other warmly before Biden signed a series of executive actions meant to combat the pandemic. He appeared for a number of television interviews. He was the first administration expert to stand in the briefing room under new management.
Fauci himself said he was guaranteed a new approach.
"One of the things that was very clear as recently as about 15 minutes ago, when I was with the President, is that one of the things that we're going to do is to be completely transparent, open and honest," Fauci said. "If things go wrong, not point fingers but to correct them. And to make everything we do be based on science and evidence."
"That was literally a conversation I had 15 minutes ago with the President," he said, clearly relieved the stark warnings he's been trying to convey about the pandemic for months would now come with the imprimatur of the White House.
"We are still in a very serious situation," Fauci said as he began his remarks, calling the recently passed death toll of 400,000 "historic in a very bad sense."
He suggested that the recent seven-day average of cases "looks like it might actually be plateauing in the sense of turning around," and the public health officials "think it's real."
But, he added, he's said this before.
"I'm sort of getting a déjà vu standing up here cause I said something like this almost a little bit less than a year ago when we were talking about the acceleration of cases in the late winter, early spring of 2020, when we were having New York City metropolitan area being the epicenter of what was going on. There are always lags, so please be aware of that," he said.
That, of course, was before Trump decided Fauci's urgent warnings were dampening Americans' spirits and, in turn, his political prospects.
By summer, Trump had taken to insisting the country was "rounding the corner" on the virus. By the time another surge hit in the fall, Trump was in full denial.
Fauci went for weeks without speaking with Trump. Two days before the election, Trump suggested to a crowd in Florida he might fire Fauci. The doctor continued to attend task force meetings with Pence, and appeared at a briefing with Pence in November, but his relationship had died with Trump -- who'd taken to a new adviser, Dr. Scott Atlas, whose views were on the fringe.
On Thursday, Fauci signaled the days of overconfidence and loose facts were over.
"One of the things new with this administration is if you don't know the answer, don't guess," he said. "Just say you don't know the answer."
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