Jess Jordan, Kendall Roy’s assistant in the HBO drama “Succession,” is finished with the permanent headache that is the Roy family.

But she could have been forgiven for bailing out much earlier than the show’s penultimate episode. Perhaps after Kendall made her take care of his children’s pet bunny. Or when he asked her to procure him drugs. Or when he gave her two minutes to summon “the best airplane medicine expert in the world” in the hope of rescuing his father, Logan Roy, who was probably already dead in the aisle of his private jet.

For the assistants on the show and their real-life counterparts, responding to the exorbitant demands of the wealthy is all in a day’s work.

“I always say I’m a mom for rich people,” said Lauriane Nagel, 28, who has worked as a personal assistant to royal families and an executive assistant to tech founders. Ms. Nagel once noticed that her yearly salary amounted to the cost of one refueling of a client’s private plane.

Ms. Nagel said she had enjoyed learning to solve the problems of the ultra rich. While aboard a family’s yacht, she once had to take care of a Pomeranian that her client had received as a gift from his stepfather. The dog spent a week at sea being doted on by Ms. Nagel and the ship’s crew while the family ignored him. A week later, Ms. Nagel said, she found a family ashore to adopt the Pomeranian.

Executive and personal assistants occupy a vulnerable perch among the powerful — proximity in exchange for a job with the likelihood of taking on challenging responsibilities, grueling hours and unimpressive pay.

Juliana Canfield, who plays Jess, said the character had little room to complain while she was at the behest of Kendall (Jeremy Strong). “She starts to want to speak her mind a little more this season, but she’s still an assistant,” Ms. Canfield said in an interview at the Season 4 premiere. “She has to respect boundaries and hierarchies.”

But the dubious call of the Roys’ news network, ATN, in favor of a “Nazi-curious” presidential candidate eventually drives Jess away. A non-billionaire and one of the only Black people in the Roys’ spheres, she tries to convey to Greg (Nicholas Braun), the family’s cousin, that the decision will have consequences for many Americans.

Onscreen portrayals of assistants often focus on the downsides of the job. In “The Devil Wears Prada,” an assistant played by Anne Hathaway performs herculean tasks, like chasing down an unpublished “Harry Potter” manuscript. Other onscreen assistants expose viewers to workplace sexism (Julia Garner in “The Assistant”) and racism (Rex Lee in “Entourage”). Most are women, and almost all — like those in “Working Girl” and “Mad Men” — are underestimated.

The real thing may not be that much cushier. Earlier this year, former employees claimed that an unattributed job listing that was widely mocked for its demands belonged to the artist Tom Sachs and his wife. The role offered $65,000 to $95,000 to a candidate who could care for a rooftop garden and a 4-year-old, and otherwise “make life easier for the couple in every way possible.” (Following reports of mistreatment in his studio, Mr. Sachs later apologized for his workplace culture in a statement to The New York Times.)

“The profession does not get the regard and recognition it deserves,” said Melba Duncan, who was an assistant to the Lehman Brothers chief executive Peter G. Peterson for nearly a decade. Ms. Duncan, who now recruits and trains other assistants, named “emotional stability and resilience” as two of the most vital qualities for the job.

Top assistants can draw salaries in the hundreds of thousands of dollars, she said. But they must be constantly available to navigate everything, including their boss’s schedules and marriages. “There are no boundaries in these relationships,” she said.

The Roy family patriarch, Logan, played by Brian Cox, becomes romantically involved with his assistant, Kerry. She also unsuccessfully tries to parlay her access to the Roy family into an on-air role on ATN.

Zoë Winters, who plays Kerry, said the character’s position in the throes of such complex personal and professional dynamics made the role especially juicy

“What I read about these media mogul families and corporations is that there’s a serious level of fandom in the room,” she said in an interview at the premiere. On the show, she added, “the ever-shifting tide of who you’re fastening your trust to and who you feel betrayed by is always surprising.”

Camille Perri, a former assistant to David Granger, the former editor in chief of Esquire, noted that the high levels of trust required between executives and their assistants could be treacherous for everyone involved. (Her own experience was overwhelmingly positive, she added.)

Powerful bosses can easily take advantage of their assistants. But as Ms. Perri explored in her 2018 novel, “The Assistants,” the underlings’ access can amount to its own kind of power. “If you’re underestimated and you’re invisible, they sort of don’t see you coming,” she said.

Irina Totok, 24, who lives in Brooklyn and worked for four years as the executive assistant to three partners at a private equity firm, said that one of her bosses once requested a pair of hiking shoes he had seen in an Instagram post. Mrs. Totok combed through comments to find the German brand that made the shoe, then traced her boss’s foot on a piece of paper to figure out his European shoe size. When the shoes arrived a month later, he did not like them.

“In a lot of TV shows, assistants are shown as superheroes,” Mrs. Totok said. “I’m very happy with that.”

On “Succession,” viewers mostly see Jess and Kerry in boardrooms and black cars. If they have lives outside of work (Is Jess in a weekend bocce league? Does Kerry binge-watch “Survivor”?), it never makes it onscreen.

At least not yet. Ms. Winters told Vulture that she and Ms. Canfield had joked about a spinoff focusing on Kerry and Jess. Maybe, Ms. Canfield said, “they’re roommates and best friends and it’s really sweet!”