Warning: Mild spoilers about "The Great" (and history) below.

Last October — or a lifetime ago — Showtime's "Catherine the Great" explored the height of the Empress of Russia's reign, as portrayed by Helen Mirren, in period-authentic, 18th century imperial dress. Now, "The Great" (out today on Hulu) depicts a very different, but also quite steamy, imagining of the powerful monarch's rise, this time played by (recent Disney Queen of the Moors) Elle Fanning.

As I was watching the satirical and anachronistic take on one of the most powerful female rulers in history, I couldn't help but think "Reign" meets "The Favourite." (The "occasionally true story," as the title disclaimer reminds us, shares an executive producer, Tony McNamara, with the latter.) It's not just the plot, either: This cheeky, modern interpretation of Catherine's pre-coup d'état time in Russia is seen in the colorfully inventive costumes by Emma Fryer, whose prior work includes '50s-set hot priest (or vicar) mystery show "Grantchester" and the 2012 miniseries "The Town" (which actually stars "Fleabag" hot priest Andrew Scott).

Fryer first dove into historical research on Imperial Russia from libraries, museums and books of original paintings to create the period-authentic silhouettes, from accurate "underpinnings" to corseted ball-gowns. She then enjoyed creative freedom given by McNamara and co-executive producer Marian Macgowan to incorporate modern-day fabrics and contemporary fashion influences, especially last year's Christian Dior retrospective at the Victoria & Albert Museum in London.

Queen of Sweden and Catherine (Elle Fanning).

Queen of Sweden and Catherine (Elle Fanning).

"[The series is] fictionalized fun, but does incorporate historical facts," says Fryer on a call. "Through the whole of the show, there's an essence of [the real Catherine the Great] as this amazing, powerful woman."

In the premiere, an optimistic, rosy-cheeked Catherine arrives from her native Prussia to marry Emperor Peter, a petty, uncultured and overly-indulged dilettante (Nicholas Hoult, reminiscent of his peacocking Lord Harley in "The Favourite"). "When she first comes to this palace, she's this idealist young girl arriving in Russia for an arranged marriage and she has all these hopes," says Fryer. "She's quite whimsical at the beginning."

Catherine's pastel palette begins in her new home country with a sky blue brocade gown and matching faux-fur accented cape. Differentiating herself from the rest of the elaborately decorated and ostentatious court, Catherine's gowns are more streamlined and adorned with "soft decoration," like delicate ruffles and subtle nature prints. Her panniers — or undergarment side-hoops — evoke the nipped-waist and sculpturally-skirted Dior Bar Suit, circa 1947, rather than the exaggerated, extended shapes from the actual period.

Catherine trying to fit in with the ladies of the court.

Catherine trying to fit in with the ladies of the court.

"She's definitely not part of this kind of mad court. It's a crazy place that she landed in — and it's bold and anarchic — and she's not part of that world," adds Fryer. "She definitely does stand out from the rest of the palace. They're very much in jewel tones and winter fruit colors: dark wine reds, gold, silver, black, burgundy, aubergines, rust." 

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The visual juxtaposition becomes very clear during an intense tea dance sequence, when Catherine tries to make peace with the trifling court ladies. Stunting in their gaudy wigs and overly-embroidered gowns with stomachers covered in velvet bows and tacky jewels, the court clique bullies Catherine, clad in soft pink floral brocade with pleated ruffle details (above).

Leo (Sebastian de Souza) and Catherine.

Leo (Sebastian de Souza) and Catherine.

Her wardrobe begins to evolve when an irritated Peter — too busy partying with his court bros and frolicking with his best friend's wife — offers a discontented Catherine a distraction. 

"When she meets Leo — when she's given Leo — the color palette changes," says Fryer. As the young Empress warms to the idea of a sanctioned side-piece, she and anatomically-gifted Leo (Sebastian de Souza) begin dressing in similar tones of greens and yellows (above), as couples tend to do. 

"I wanted to bring those two characters together as their relationship evolves through the episodes," adds Fryer.

The intelligent, erudite and increasingly confident Catherine also brings a jaunty 18th century version of a borrowed-from-the-boys look into her wardrobe, which was inspired by a relaxed, undone menswear fashion spread. Fryer translated the self-assured, effortless sensibility onto Catherine with a swashbuckling, open-neck and puff-sleeve blouse tucked into a voluminous ball-gown skirt and cinched at the waist with an embroidered belt (below). 

"It was just to give her a much more relaxed feel and keeping her youthful," says Fryer.

Marial (Phoebe Fox) and Catherine.

Marial (Phoebe Fox) and Catherine.

Catherine's take on separates feels especially befitting for bolder moments, like sipping Moscow Mules with Leo by the fountain, teaching a young servant how to read or clapping back to the patriarchy during a scene with creepy Archbishop (or "Archie," Adam Godley).

In a contrast to Catherine's romantic, whimsical aesthetic, Peter's style exhibits unpredictability and volatility, similar to his personality. "He has this crazy punk rock 'n' roll look," says Fryer. "The character is insecure and sulky, not really a bad guy, but a bit of a mama's boy. He runs this chaotic and completely debauched court." 

Fryer maintained 18th century silhouettes on Peter, but heightened his look with a mixture of "animalistic" prints (like leopard, cougar and crocodile) and 21st century textures and fabrics.

"It was a real world of mismatching with him. But mismatching, I hope, in an interesting and wonderful way," she says. "I chose these really fantastic linings that had a sense animal print and then his britches were always either gold or bronze." 

Peter (Nicholas Hoult).

Peter (Nicholas Hoult).

Peter also has a penchant for wearing his dead — but still close by — mother's pearls when he's feeling a tad vulnerable. Mama's boy, you know? 

"Because the mom is in the cabinet, so he always goes back to his mommy to ask her [for advice]," says Fryer. "[McNamara and I] often had chats, 'Ooh, should we wear the pearls? Would it be right for it in this scene, though?' Peter didn't wear them that much, but it was more for an occasion." In one frenzied scene, his layered necklaces, low-slung leather pants, an open brocade robe and no shirt all give off a very '70s Mick Jagger or Jared Leto right now kind of vibe. 

In what felt like a nod to the gender-swapping costume extravaganzas that these emperors and empresses famously threw in real life, Peter debuts a skirt for a festive ball scene, to which this version of Catherine attempts flattery: "It is very pretty." (The libidinous Peter's purpose, however, is more about functionality, to allow for his genitalia "to swing free in the air." Huzzah!) 

In an initial fitting, Fryer initially tried a period-authentic ball-gown skirt with panniers and proper foundation garments on Hoult, but ultimately landed on a contemporary, asymmetrical wrap-front style, which aligned with the definitely not 18th century, "The Favourite"-style choreography. 

"He had to do high kicks," says Fryer. "Then we had this conversation, 'Should he wear boots with the skirt? Should he still wear the shoes with the skirt?'" (Final decision: boots, as pictured below.)

Catherine and a free-flowing Peter, in his mom's pearls and his own skirt. 

Catherine and a free-flowing Peter, in his mom's pearls and his own skirt. 

As Catherine's journey to unseat her husband and rule Russia progresses, her palette begins to darken, culminating in a foreboding, inky navy and a shockingly bright pink. "I wanted determination and optimism," explains the costume designer. "She's determined to become this great leader."

The turning point could be visually marked by Fryer's favorite design: a dark teal and faux fur-accented wool coat detailed with royal purple tassels on the bodice (second from top). Catherine wears the majestic, floor-length layer to accompany Peter on an important meeting to negotiate a truce with the king and queen of rival Sweden. 

"Once we ended up with the hat and all the accessories, I thought, 'Oh, she's going to end up being the ruler of Russia.' It just gave her a bit of gravitas," says Fryer. "From how we saw her at the beginning, as this young whimsical woman and, suddenly, there's a nod towards where she was going to go — and what she's going to achieve, as this determined, intelligent woman."

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