In 2016, Corey Lewandowski was fired by Donald J. Trump’s campaign for encouraging the candidate’s undisciplined habits.

Then he made his way back into Mr. Trump’s orbit.

In 2021, Mr. Lewandowski was ousted from Trump world again after he was accused of making unwanted sexual advances on a Republican donor.

Now he has made his way back yet again, in a move that has puzzled some of Mr. Trump’s allies.

The sometimes-volatile Mr. Lewandowski has been given a position on the campaign as an adviser. But he is something of a minister without a flock, with vague responsibilities and an uncertain portfolio.

Mr. Lewandowski’s well-documented temper, impulsiveness and misogyny make him easy to portray as a potential conduit for Mr. Trump’s own recklessness — and help explain why Mr. Trump’s wife and children generally loathe him, according to people close to the family.

But one of the truisms of Trump world is that the only permanent exile is self-imposed. And Mr. Lewandowski has always found a way to regain Mr. Trump’s trust and tunnel his way back in.

Without the authority to spend money and with no staff members reporting to him, Mr. Lewandowski, who turns 51 on Wednesday, has little opportunity to make changes directly. As a result, he’s widely viewed as a potential chaos agent among aides who fear that his word carries an implied stamp of approval from the former president.