President Trump's niece, Mary Trump, offered a bleak picture of her family's purportedly toxic dynamic, telling ABC that her "sociopath" grandfather, Fred Trump Sr., taught his kids to treat other people as "expendable."

"He had no empathy," she said in an interview that aired Wednesday. "He was incredibly driven in a way that turned other people, including his children, his wife, into pawns to be used to his own ends. If somebody could be of service to him, then he would use them. If they couldn’t be, he excised them."

During her interview, Mary Trump indicated that both she and her father, Fred Trump Jr., were pushed to the margins of the family. Before publishing the book, she faced a lawsuit from her other uncle, Robert Trump, who claimed she was barred from discussing certain information after signing a nondisclosure agreement as part of a testy battle over Fred Trump Sr.'s will.

STEPHANOPOULOS PRESSES MARY TRUMP ON WHY SHE VISITED WHITE HOUSE IN 2017 AND WHAT SHE TOLD HER UNCLE

According to Mary Trump's telling, she got a raw deal after her grandfather died, and her family showed an excessive focus on money at the time.

"I'm a Trump. Everything's about money in this family, but I’m also different from them, and for me, what I understood and one of the reasons it was so devastating, was that money stood in for everything else. It was literally the only currency the family trafficked in," she said.

Mary Trump's interview came after she released a memoir with explosive allegations about her uncle as he ran for re-election. More specifically, she alleges that Donald went to see a movie while his older brother and Mary's father died alone in the hospital.

Mary Trump said she found out about her father's death after Fred Sr. called and told her that his eldest son was in the hospital, but that it wasn't "serious." "Two minutes" after that call, Mary Trump said, she found out from her mother that her father had actually died two hours prior. She also alleges that her grandparents stayed at home rather than being with their son at the hospital.

MARY TRUMP'S TELL-ALL BOOK COMES OUT CLAIMING TRUMP CHEATED ON SAT TEST

"I will never know why they didn't go to the hospital to be with their son -- who was clearly dying," she said of her father. "So, maybe it isn't surprising that Donald didn't think he needed to be there. Maybe that would have looked bad to his father and maybe, sitting around waiting for the phone call was too burdensome -- I don't know. But, you know, I've often wondered what movie did he go see that seemed more compelling than sitting with his dying brother."

Those were just some of many headline-grabbing revelations from the niece of one of the most powerful men in the world. Others include that a man named Joe Shapiro allegedly took President Trump's SATs for him.

The White House has vehemently denied this accusation and alleged the book was full of "falsehoods."

Despite a legal threat and protest from her own family, Mary Trump decided to speak out about the danger she thought her uncle posed to the country. At the beginning of July, a New York Supreme Court appellate judge ruled that Trump's niece could release her 200-page missive on the family dynasty. Released on Tuesday, the book is titled "Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man."

MARY TRUMP TELL-ALL CAN MOVE FORWARD WITH PUBLICATION: JUDGE

Trump's purported callousness, she said, stemmed from her grandfather's influence, which suppressed feelings of sadness and a spark of kindness in her uncle.

"One of the unforgivable things my grandfather did to Donald was he severely restricted the range of human emotion that was accessible to him," Mary Trump, a clinical psychologist, said.

She added that "certain feelings were not allowed." That included "sadness, the impulse to be kind, the impulse to be generous -- those things that my grandfather found superfluous, unmanly," she said in the footage released by ABC.

On Wednesday, Trump's son Eric tweeted an apparent attack on his cousin Mary.

CLICK HERE TO GET THE FOX NEWS APP

"Every family has one...," he tweeted. "It’s usually telling when that 'one' stands alone."