King Charles and Queen Camilla Are in a 'Constant Battle' at Home as They’re 'Polar Opposites'

King Charles and Queen Camilla 's marriage is pretty normal, the Queen's sister revealed.

Camilla's sister, Annabel Elliot , gave insight into the couple's life at home.

According to Elliott, the royals are "polar opposites" and often disagree about sleeping with the windows open.

"There's a constant battle about it," Elliot told Robert Hardman . "He will have opened it. She will creep in behind and shut it. So there's a lot of: 'Oh, darling, you shut the window,' 'Yes, I have, because we're all freezing.' So a lot of banter goes on."

Elliot shared that Charles "usually wins on that front," but Camilla "wins most other things ."

"The King dislikes being inside for too long and always has the windows wide open," she explained. "A meeting at Birkhall , his home in the Highlands, in the middle of winter was not for the faint-hearted."

"I can remember more than one occasion when I thought I might have actually got frostbite while trying to write with a hand I could no longer feel," Elliot added.

Although the royals have different habits, they are expected to spend quality time together in Scotland. OK! previously reported they will reunite at Balmoral for their summer break.

"Birkhall is like a second home to both of them, they absolutely adore it," a source told an outlet.

"Not only is it where they had their honeymoon but also where they both enjoy spending time together away from prying eyes," the insider shared.

Princess Diana famously branded Camilla as the third person in her marriage, and Prince Harry threw jabs at his "wicked stepmother" in Spare .

"When Harry branded his stepmother Camilla a 'villain' in his book and revealed that both he and William initially begged their father not to marry her, Harry committed what Charles regards as a cardinal sin," Christopher Andersen told an outlet after a source claimed the duo aren't in communication.

"No one disses Camilla in royal circles and gets away with it – not even a son of the king," Andersen warned.

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Harry visited Charles in February, but they failed to reunite during the duke's May trip to London.

"I think Charles could forgive Harry for some of the trouble he’s caused – including bailing on the monarchy … slamming his brother William for bullying behavior and suing for royal protection when visiting the U.K.," Andersen continued. "But Charles is having a hard time forgiving Harry for taking what he sees as gratuitous potshots at his beloved Queen Camilla."

"This still remains a thorn on the king’s side," he added.

Currently, Harry is fighting to obtain personnel privileges, and sources claim his security concerns are causing friction between him and Charles.

"He gets 'unavailable right now,'" a friend told a publication. "His calls go unanswered. He has tried to reach out about the King's health , but those calls go unanswered too."

Elliot was quoted in King Charles: New King. New Court. The Inside Story .