• Lady Colin Campbell said Princes Charles and William have "embraced their destiny and lived up to their responsibilities"
  • The royal pundit suggested Prince Harry and Meghan Markle "betrayed" themselves and their ideals for "worldly gain"
  • Harry previously said that his father and brother were "trapped" in the "system" and can't leave the way he did

Royal biographer Lady Colin Campbell believes Prince Charles and Prince William's duties and responsibilities in the monarchy give them a sense of fulfillment.

Campbell, author of "Diana in Private," "Meghan and Harry: The Real Story" and several other books on the British royal family, threw shade at Prince Harry and Meghan Markle once more in a new Q&A video uploaded to her YouTube channel.

In the video, Campbell read a remark from a royal fan who claimed that the supposed "trapped" future kings, Prince Charles and Prince William, "seem so happy with both their duties and wives," while the Duke and Duchess of Sussex allegedly "look miserable."

Weighing in on the comment, the royal pundit and Jamaican-born British TV personality referenced "Doctor Faustus," the 16th-century play by Christopher Marlowe. "That's what happens when you enter into Mephistopheles and bargain. It's a fairly standard thing," Campbell claimed.

In the play, Faustus, a doctor who is disillusioned with life and frustrated due to the limited scope of man's knowledge, decides to sell his soul to the devil in exchange for 24 years of life with power over the demon Mephistopheles, an agent of Lucifer.

"When people embrace their destiny and live up to their responsibilities, their duties, they are happy. That is what fulfillment is partly about," Campbell said.

She further claimed, "You cannot be genuinely fulfilled if you are hawking your wares to the highest bidder. Altruism and prostitution are not very comfortable bedfellows nor is betraying yourself and your ideals and the requirements of your destiny for worldly gain."

Last year, Prince Harry and Markle stepped back from being full-time royals, saying they wanted to "work to be financially independent." The couple has since signed multimillion-dollar deals with Netflix and Spotify, as well as book deals.

During the Sussexes' interview with Oprah Winfrey in March, Prince Harry said that his father and brother can't leave the "system" the way he did.

"It's been really hard," he explained. "I am part of the system with them, I always have been, but I guess — and I'm very aware of this — my brother can't leave that system, but I have."

When asked if his older brother — who is second in line to the British throne — wanted to leave the royal family, Prince Harry replied, "I don't know. I can't speak for him."

According to the Duke of Sussex, he "didn't see a way out" of the royal family before meeting Markle. "I was trapped, but I didn't know I was trapped. Trapped within the system like the rest of the family," he said. "My father and my brother are trapped. They don't get to leave, and I have huge compassion for that."

However, royal expert Katie Nicholl previously shared that sources close to Prince William said the future king was not pleased with his younger brother's statements.

"We've ... heard through friends of William who have spoken to the newspapers over here that he really rejects that suggestion from his brother that he feels 'trapped' by the firm, that he feels trapped by his future role," Nicholl told Entertainment Tonight. "If you speak to the sources close to William, they say this is very much not the case. He's very willing to embrace his destiny as a future king, and he's very happy to step up to his responsibilities."

Prince William is currently busy with his royal duties and his new project, the Earthshot Prize, which focuses on finding solutions to existential environmental challenges.

The "Earthshot Prize: Repairing Our Planet" limited series will air on Discovery on Oct. 16 beginning at 4 p.m. EDT. Prince William will then announce the first set of Earthshot Prize winners during an award ceremony that will be streamed live on Discovery's Facebook page on Oct. 17.

Prince Charles Prince William and Prince Harry
Prince Charles, Prince William and Prince Harry visit the tunnel and trenches at Vimy Memorial Park during the commemorations for the centenary of the Battle of Vimy Ridge on April 9, 2017 in Vimy, France. Getty Images/Tim Rooke