'Bridgerton's' Queen Charlotte explains King George III's mysterious illness

• On season one of Netflix's "Bridgerton," King George III (James Fleet) has a mysterious illness loosely based on the monarch's condition in real life.
• Golda Rosheuvel, who plays Queen Charlotte, told Insider that during filming they "never discussed" a diagnosis for her onscreen husband, but the portrayal came from show creator Chris Van Dusen's "mind" since "Bridgerton" isn't a biopic.
• The actress added that she and Fleet did factor in historians' theories that George had bipolar disorder and porphyria, a genetic blood disorder.
• "Back then in the 1800s, they wouldn't have known what bipolar was," Rosheuvel explained. "The unknown of that would be terrifying, I think. The outbursts would be terrifying."

Netflix's new addictive series "Bridgerton" portrays Regency England, or the early 1800s, as an indulgent playground for society members, fueled forward by "ambitious mamas" and anonymous town gossips.

Even though Chris Van Dusen, the show's creator, twisted history while creating the pastel-painted universe, he did incorporate King George III's mysterious illness.

The monarch, who has been coined as the "mad King who lost America" in real life, scarcely appears on screen. When he does, embodied by actor James Fleet, he displays manic behavior.

"Where on Earth do they keep him anyway?" Prince Friedrich (Freddie Stroma) asks of his uncle in episode three.

George's illness is somewhat of an enigma on "Bridgerton" and is mostly viewed through the eyes of Queen Charlotte, played by Golda Rosheuvel.

The actress told Insider that she and Van Dusen "never discussed" the specifics of her onscreen husband's condition.

"It was just from Chris' mind," she explained, pointing out that the series, produced by Shondaland, isn't a royal biopic, but rather a reimagined version of history. Rosheuvel added that they factored in historians' theories that George had bipolar disorder and porphyria, a genetic blood disorder that can cause confusion, hallucinations, and paranoia.

"Back then in the 1800s, they wouldn't have known what bipolar was," Rosheuvel noted of the mental disorder that's marked by extreme mood swings. "The unknown of that would be terrifying, I think. The outbursts would be terrifying."

It may seem like the King's condition is a mere subplot in a series that revolves around the high stakes social season of 1813, but Rosheuvel felt like there was a "real importance" to show the royals' dynamic in order for viewers to better understand the Queen.

"In public, it's very lavish. It's very fun. It's very naughty. It's very regal. There's a position of power. In private, I think you see her as a real human being who desperately, desperately, desperately loves her husband and is having to deal with the unknown," Rosheuvel said. "She's a rounded character."

During most of Charlotte's scenes, she's a stoic figure commanding the room in towering wigs and ornate ball gowns. And while she enjoyed playing the meddling Queen on a hunt for Lady Whistledown, the "Gossip Girl"-esque narrator (voiced by Julie Andrews) behind the town's society papers, Rosheuvel said the most memorable scene to film was between her and Fleet.

In episode five, the couple shares a rare interaction over dinner. Charlotte tells her husband that both she and his subjects "miss" him, and he reacts with confusion, explaining that he's right in front of her.

When George asks about their daughter, Amelia, Charlotte gently reminds him that she died several years prior. (In real life, Amelia, who was reportedly the King's favorite child, died after contracting tuberculosis.)

The King then lashes out and throws his dinner plate to the ground, accusing Charlotte of killing Amelia.

"That was the first scene I did with him," Rosheuvel said, referring to her costar. "Before then, it had been balls and balls and tea parties and tea parties. It was the first time that I could show her intimate side and her private side and I was really excited for that to be seen by people."

Season one of "Bridgerton," also starring Phoebe Dynevor, Regé-Jean Page and Adjoa Andoh, is streaming on Netflix now.