'Bridgerton' author Julia Quinn says Anthony's affair with Siena was headed for disaster but sets him up for season 2

• Julia Quinn spoke to Insider about Anthony's relationship with Siena on season one of "Bridgerton."
• The author doubted the couple would have worked out but said the affair set Anthony up for season two.

In Julia Quinn's mind, Anthony Bridgerton's season-one affair with Siena Rosso on Netflix's "Bridgerton" was merely teeing him up for his true love, Kate Sharma.

"I don't know how much he was in love with Siena, or the idea of her," the 51-year-old author of the Bridgerton book series recently told Insider while promoting her new project, "The Wit and Wisdom of Bridgerton: Lady Whistledown's Official Guide," published Tuesday.

A character named Maria Rosso is briefly mentioned in Quinn's second "Bridgerton" novel, "The Viscount Who Loved Me" (2000), as one of Anthony's distractions from looming marital commitment.

But after the novelist handed over creative control of her story to Shondaland, Maria turned into Siena, an on-screen version of the operatic soprano played by Sabrina Bartlett. She assumes a much larger role on the show, forming a full-on clandestine relationship with the young viscount (Jonathan Bailey) on the debut season.

However, Anthony and Siena's relationship is complicated from its inception. As the eldest Bridgerton, the viscount is expected to court a lady, and the rising star doesn't fit the bill.

Siena never really stands a chance as a serious marriage prospect for Anthony, due to 19th-century London's rigid social hierarchy.

"Had they tried to be together, it would have been very problematic and it would have been difficult. So, I thought it was nice. It just sets him up. It helps build his character in a way to give it more depth than perhaps he got in the first book in the series," Quinn said, referring to "The Duke and I," which served as a guide for showrunner Chris Van Dusen's first season.

She added, "That's another thing that's great about the television series is that the secondary characters get even more airtime. We are more invested with them earlier on than we can be in the books."

Anthony and Siena's entanglement, though ill-fated, does prepare the viscount for his forthcoming romance with Kate, a debutante that enters London's marriage market in 1814.

"He's ready to fall in love with somebody who can be his match in a way that Siena can't," the author said, adding that the singer's lack of title and status in no way minimizes her strength and impressive self-advocacy.

In line with Quinn's novels, which each focus on a different Bridgerton sibling's romantic endeavors, the show introduces a new couple on every season.

Since Simon Basset (Regé-Jean Page) and Daphne Bridgerton (Phoebe Dynevor) find their happily-ever-after on season one, just as they do in Quinn's "The Duke and I," the next chapter moves on to Anthony and Kate (Simone Ashley).

And theirs is a different type of tale.

"It's more of an enemies-to-lovers story than 'The Duke and I' was," Quinn explained. "They're much more antagonistic at the beginning, but in a fun way."

She continued: "I hate the stories where these people are saying, 'I hate you. I hate you, I hate you,' and then they're like, 'Why can't you tell that I love you?' And you're just like, 'You guys are going to get divorced.' This is not that."

"You totally see them falling in love and you believe it, but you get a lot of really great verbal bickering."

Season two of "Bridgerton" recently wrapped production, but Netflix has yet to announce an official release date.