A powerful media family is torn apart by jealousy and rivalry. A granddaughter rushes to the aid of the aging patriarch as he publicly wastes away. Lies, betrayal and complaints.

These are not the machinations of the fictional Roy family from “Succession,” but the dramas involving the very real Redstone clan, whose well-documented dysfunction served in part as inspiration for the critically acclaimed HBO series.

But those deep rifts – most notably between Paramount Global overlord Shari Redstone and her niece Keryn Redstone – may soon be healing, thanks to the impending windfall from handing over the reins to the media and entertainment giant.

The Redstones are expected to make $1.75 billion in the hit-and-miss deal with Skydance Media for their 77 percent stake in National Amusements, the family-owned company that controls Paramount.

Keryn Redstone, 42, is expected to receive around $140 million – a final gift from the grave of media giant Sumner Redstone as her share of a trust fund he set up for his five grandchildren, sources told The Post.

Capricious mogul Keryn, affectionately known as “Grumpy,” became a dominant force in the media world by transforming his father’s 14 drive-in theaters into hundreds of movie palaces.

He then used the profits he made to buy relatively small shares in media companies and resold these shares in the 1980s at a huge profit.

His next move was to buy up media companies like CBS and Viacom through bitter takeover battles and sheer determination before his health failed in the mid-2010s – and Keryn Redstone came to his aid.

“I had a difficult but authentic relationship with my grandfather,” Keryn Redstone told The Post in an exclusive interview. “He had such a strong sense of humor.”

He could also be ruthless. Sumner is pitting his two children, Shari and Brent Redstone, against each other in their own succession battle, which continues as Paramount Global – the company he created from CBS and Viacom – nears its end.

Keryn Redstone is the older of Brent’s two daughters, and despite her seemingly idyllic childhood in one of the wealthiest families in the country, she has her own problems.

She grew up near the family estate in Massachusetts before her father moved the girls to a 625-acre ranch in rural Evergreen, Colorado, when she was 11.

She and her sister Lauren, now 38, attended a private school in Colorado that required a five-hour commute each day, Keryn said.

After graduating, she moved to New York, where she earned a degree in film and television from NYU in less than two years before going on to earn a law degree from the University of Denver.

While she was studying law, one of the first salvos in the family dispute over the succession to the throne came when her father sued National Amusements.

Brent refused to give up his Paramount voting stock to his father, who was going through a divorce and wanted to keep control of the company. Shari supported her father’s plans against her mother’s wishes.

According to media reports, Brent agreed to a settlement of approximately $240 million with National Amusements in 2007, but waived all claims to future payments in the event of a sale of the company.

Sumner retained control of Paramount.

Despite the estrangement between father and son, Keryn remained close to Grumpy.

She often traveled from her home in Colorado to stay at the mogul’s Los Angeles mansion overlooking Beverly Hills.

During this time, she became friends with the tycoon’s much younger partner and caregiver, Manuela Herzer, according to the book “Unscripted: The Epic Battle for a Media Empire and the Redstone Family Legacy” by James Stewart and Rachel Abrams.

Herzer played a key role in further tearing the Redstone family apart during a bitter legal battle between his girlfriend and Shari as her father’s health deteriorated.

In 2016, Keryn sided with Herzer, claiming her aunt pushed for a do-not-resuscitate order during her father’s hospital stay, court records show.

“Shari and her family have succeeded in completely isolating my grandfather due to his weakened mental state and fragile health and have effectively kidnapped, brainwashed and exploited him,” she said in a June 2016 statement.

“Shari and her three adult children have succeeded in reversing my grandfather’s decades of careful estate planning and are on the verge of taking control of Viacom and CBS.”

Keryn had moved into the Los Angeles mansion the previous year at the request of Herzer and her grandfather when Sumner’s health rapidly deteriorated, she added in her statement.

“My grandfather and I have had a very close and loving relationship since I was a child,” Keryn said at the time.

In exchange for her moving in, Grumpy set up a $1 million trust fund for Keryn, allowing her to spend the proceeds from the capital, according to Unscripted.

The court battle revealed a lot of the Redstones’ dirty laundry, including an alleged death threat from Shari against Keryn during Sumner’s 91st birthday party in 2014, his granddaughter claimed in the lawsuit.

Keryn was sitting next to Sumner because he had injured his hand and asked her to stay close so she could help him eat, Keryn said in court documents.

Shari tried to sit next to him and when Keryn refused to move, her aunt threatened to kill her, court documents say.

“I am sad and disappointed that Keryn has chosen to side with Herzer against my father,” Shari’s spokeswoman said at the time.

During this time, according to the Wall Street Journal, Sumner Redstone communicated via an iPad that had audio clips of his voice preloaded with him saying “yes,” “no,” and “fuck you.”

Shari banned Keryn and Manuela from entering Sumner’s home and won the legal battle in 2019. Herzer agreed to repay the Redstone family $3.25 million – a fraction of the money the billionaire gave them in his final years.

In her recent interview with the Washington Post, Keryn took some responsibility for turning against the family.

“I am responsible for my actions, but they did everything to make my life difficult,” she complained.

Sumner died in 2020. He was 97.

After his death, Keryn Redstone led an unsettled life, moving into rental apartments in Colorado, Northern California, Pennsylvania and Virginia, she told The Post.

She has also tried her hand at film, being credited as one of the executive producers of the 2021 horror film The Last Thing Mary Saw alongside Scoop, daughter of the late Bruce Wasserstein.

Set in 1843, the film tells the story of the murdered strict family matriarch and the role played in the murder by her youngest daughter, who had a relationship with the maid.

Shari Redstone meanwhile took control of Sumner’s business and completed the CBS-Viacom merger in 2019.

Under Shari’s leadership, Paramount Global’s value shrank from a market capitalization of $31 billion at the time of the merger in December 2019 to $8 billion today.

Paramount’s 45-day “go-shop” window ends on August 21, before the company is expected to accept Skydance’s offer.

The Sumners’ five grandchildren will receive 40 percent of the proceeds, or about $140 million each, sources with knowledge of the patriarch’s will told the Washington Post.

Sheri Redstone, 70, has three children – Tyler Korff, 38, Brandon Korff, 40, and Kimberlee Ostheimer, 42.

The 99-year-old ex-wife Phyllis Redstone will also receive 40 percent of the proceeds, while Shari will pocket the remaining 20 percent, or about $350 million, the sources added.

Phyllis has most recently been living in one of the bungalows at the Beverly Hills Hotel in California, a source told The Post. It is not known who will inherit her considerable fortune. According to the Los Angeles Times, she also received a $100 million cash settlement after her 52-year marriage to Sumner Redstone ended in divorce in 2002.

While Keryn has not yet reconciled with her celebrity aunt, she said she now has a good relationship with her cousin Tyler Korff, an ordained rabbi.

Keryn declined to comment on what the future might hold if she wins the big check from a sale of Paramount.

Keryn said she loves animals and wants to be with them.

“Give me 1,000 horses, cats and dogs and I’ll be happy,” she said.