After working for Ivanka and on various Trump Organization real-estate projects, "Mr. Trump sat her down and said, 'This is your new job, '" Hicks's mother said in a June 2016 New York Times profile of her daughter.
She is one of six White House staff members who Mueller might want to meet.
Since he took office, President Trump has reportedly come up with a few rather cozy nicknames for Hicks-including "Hopie".
Hicks was Trump's director of strategic communications, she also served as his press secretary at the start of the presidential campaign. She has only tweeted three times.
According to Politico, Hicks, 28, was initially hesitant to take the position permanently and demanded that interim be but into her job title. As Hicks once said of Trump, "He is brilliant with a great sense of humor, and an awesome ability to make people feel special and aspire to be more than even they thought possible".
While Mr Trump has already fired or dismissed several of his aides during the first leg of his administration, Ms Hicks has been labelled by the media as "untouchable".
Her relationship with the Trump family began while she was an employee of Hiltzik Strategies, a NY public relations firm, where she worked on projects for Ivanka Trump, the President's eldest daughter.
Anthony Scaramucci, who was named White House communications director in July, meanwhile, left the job just days after joining the Trump Administration.
The Greenwich, Connecticut, native is Trump's third communications director, following Scaramucci and Mike Dubke, who announced his resignation in May. But despite the ostensibly temporary nature of her initial appointment, no active search for another communications director had been conducted as of late August. Hicks is a 2010 graduate of Southern Methodist University, where she majored in English and played club lacrosse.