Per an official description shared by Starz in February 2023, the series will "center on these two parallel love stories set in two different time periods, with Jamie's parents in the early 18th century Scottish Highlands and Claire's parents in WWI England."

The streamer had previously stated that the prequel would center on Jamie's mother and father, Ellen MacKenzie and Brian Fraser — two characters that audiences know plenty about, mainly through stories told by their son.

An abridged version of Ellen and Brian's love story was detailed by Jamie in season one: the pair eloped together and stayed hidden until Ellen was visibly pregnant with their first child, forcing her family to accept their union.

The decision to include Claire's parents in the show is sure to be a welcome one. Not much is known about Julia Moriston and Henry Beauchamp beyond the fact that they died when Claire was a young girl.

"We're thrilled to be telling the stories of these two couples," said Matthew B. Roberts, showrunner, executive producer and writer on both "Outlander" and "Outlander: Blood of My Blood."

"The origins of their relationships explore universal themes that transcend time periods, and we're so excited for fans to discover and fall in love with these characters and their love stories the way they have with Claire and Jamie."

Harriet Slater, best known for her role in "Pennyworth," will play Jamie's mother, Ellen MacKenzie, in the 18th-century Scotland storyline, alongside Lifetime actor Jamie Roy, who plays his father, Brian Fraser.

As for Claire's parents, whose story unfolds in World War I-era England, Hermoine Corfield, previously seen in "Mission: Impossible - Rogue Nation," will play Julia Moriston; "Mamma Mia! Here We Go Again" actor Jeremy Irvine will play her father, Henry Beauchamp.

The two stars have previously worked together, having both starred in the 2016 fantasy romance film "Fallen."

As the showrunner stated, the series will take place in two different time periods.

The story focusing on Brian and Ellen will be set sometime around 1716, some 30 years before Claire travels back in time and meets Jamie. That's when the Great Gathering at Castle Leoch happened — which is where Brian and Ellen met for the first time — according to the "Outlander" books.

That would make our heroine Ellen and her future husband Brian both 25 at the time the series begins, as they were both born in 1681, per details shared in "Dragonfly in Amber." 

The other story about Claire's parents is likely to take place sometime in the 1910s. As fans know from the first book installment, Claire was born in 1918 and was five years old when her parents passed away in 1923. Exact details on when her parents met or how old they were are not known.

The author has confirmed that, alongside writing what is expected to be the tenth and final novel in the "Outlander" series, she is also working on several other stories connected to Jamie and Claire, including a prequel novel about Jamie's parents.

The book does not yet have a title, but Gabaldon told the audience at the 2022 Edinburgh International Book Festival that it includes romance and plenty of historical intrigue.

"The story is woven in with the Jacobite Risings – there will be a lot of clan politics and other interesting things," she said, per The Scotsman.

For those who are interested, she has shared several excerpts of the book with her Facebook audience.

As for how the show's producers are working with Gabaldon and her unfinished novel, executive producer Maril Davis told Business Insider in August: "We hope she will share as she goes, but we've kind of been taking the breadcrumbs she's left in her books and expanding on those to build a story."

The author has also shared with TV Insider that she will be writing an episode of the prequel in addition to writing an episode for "Outlander" season eight.

In a press release from January 2024, Starz announced that "Outlander: Blood of My Blood" had been greenlit for a 10-episode season.

It hasn't been confirmed if that means the series will be a one-off or whether viewers can expect more seasons after "Outlander: Blood of My Blood" airs.

Representatives for Starz did not respond to Business Insider's request for comment.

If you were wondering what "Blood of My Blood" means exactly, it's a phrase that "Outlander" fans know well, as it's part of the Gaelic blood vow that Gabaldon created that Jamie and Claire exchanged on their wedding day.

'"Ye are blood of my blood, and bone of my bone, I give ye my body, that we two might be one. I give ye my spirit, 'til our life shall be done."

But before you get too excited, keep in mind that since the Brian and Ellen timeline part of the prequel will be set nearly three decades before the events of the main series, the same actors won't be playing the roles.

Some characters audiences will be familiar with who will appear in the prequel are younger versions of Murtagh Fitzgibbons Fraser (Rory Alexander), Dougal MacKenzie (Sam Retford), Colum MacKenzie (Séamus McLean Ross), and Ned Gowan (Conor MacNeill). The roles were originated by Duncan LaCroix, Graham McTavish, Gary Lewis and Bill Paterson, respectively.

Red Jacob MacKenzie, the Laird of Clan MacKenzie and father to Ellen and her brothers, will be played by Peter Mullan, while Tony Curran will portray Simon Fraser, also known as Lord Lovat, Brian's father.

In an interview with Esquire, Sam Heughan said that while he's definitely not in the show, there's a chance a younger version of his character could be.

"All I can tell you is I'm not in it, as Jamie's not in it," he said. "I believe that it's a prequel focusing on Jamie's parents when they were younger, so I guess you might see a young version of him at some point."

If the story of his parents does kick off around 1715 as we suspect, that's six years before Jamie's birth in 1721, meaning that audiences shouldn't expect him to come into the series straightaway. Brian and Ellen had two other children before he was born, after all.

In January 2025, Starz announced that the prequel will premiere sometime in summer 2025.