SPOILER ALERT: This story discusses major plot developments from this season of “Sirens,” now streaming on Netflix.

Meghann Fahy is on a career hot streak, starring in buzzy series like “The White Lotus” and “The Perfect Couple” and films including “Your Monster” and “Drop.” Many of her characters are known for being perfectly coiffed, elegant women who are hiding secrets to keep up appearances. Yet Fahy lights up when discussing her new role on the series “Sirens” — one that is completely against type.

“Devon is one of my favorite characters I’ve ever played,” she says. “There’s something so liberating about her, because she is so relentlessly herself, regardless of her environment. She says what’s on her mind, and doesn’t think about how other people feel about that. Which is certainly not how I move through the world.”

“Sirens” — from “Maids” creator Molly Smith Metzler — is the story of Fahy’s Devon, a blue-collar woman caring for her increasingly ill father, Bruce (Bill Camp), who heads to a mysterious New England property to confront her sister, Simone (Milly Alcock). Simone is the dutiful personal assistant for an ultra-wealthy socialite named Michaela (Julianne Moore), whom Devon thinks might also be a murderous cult leader. Needless to say, when the outspoken, combat-booted Devon lands at the front door of Michaela’s ultra-chic, pastel world, there is a battle of the wills.

In key moments in the show, Devon and Michaela square off, as the two continually argue about who is closer to Simone, and debate whether she should head home to Buffalo to help take care of Bruce. Fahy says that she was blown away by her iconic scene partner’s generosity in those moments.

“Having to call Julianne Moore some of the names that I call her on this show was the craziest experience I’ve ever had on a set,” she says. “It was very surreal to just make eye contact with her, generally. But she’s even better than you could imagine, and so grounded and generous and a true pro. I just did my best to follow her lead.”

Despite their tête-à-têtes during the series, one of the final scenes shows both women taking a solemn ferry ride away from the estate, as Michaela’s husband Peter (Kevin Bacon) abruptly dumps her for Simone. As both Devon and Michaela float away defeated, there is humility and understanding between them, far softer than in any of their previous interactions.

“That scene for me was very moving,” Fahy says. “I loved that it was this moment where these two women were acknowledging that they misjudged the other and, in their own way, apologizing for it and wishing the other well on whatever their journey was going to be after that. It’s such a powerful note for the show to end on, because I think there’s a lot of misunderstanding happening on the show. It’s one of the themes, and to see these women acknowledging that was powerful.”

The grief both characters display when leaving Simone speaks to the connections Alcock was able to make with her fellow actors. Although the two sisters present completely differently — Devon is a hard-drinking shit-talker who uses sex transactionally, while Simone focuses on working hard, preppy outfits and her type-A drive — both personalities were developed as a result of serious trauma from when they were children.

“We did spend a bunch of time together, and it was an easy sisterly dynamic from the beginning,” Fahy says. “I felt very protective of her, sort of naturally in the way that Devon does on the show too. At one point we filmed in New York, and I live there. So when she came to town, I couldn’t wait to hang out. I was dragging her all around the place, and was always joking that I was the older sister who always wanted to hang out while she was like, ‘I have plans in Williamsburg!’”

This natural sisterly dynamic allowed for a flexible emotional canvas, which was helpful as the series’ full plot was mysterious to the actors even as they started production.

“What was interesting was we were well into filming before we knew where it was going,” Fahy says. “We didn’t know how it was going to end. We had three blocks: We shot the first two episodes together, the second two episodes together, and then the final episode on its own. We had three different directors. So it was kind of an incredible reveal when we got the finale script and said, ‘That’s what happened!’

“I was so surprised to hear that Simone ends up with Peter, but the more I thought about it, the more I said, ‘You know what? This feels realistic to me,’” she say. “It makes sense to me that Simone would think, ‘There’s no way in hell am I going back to Buffalo. I will do anything that it takes to avoid that.’ It also felt true to me that Devon would go home. There’s a powerful moment when Devon says goodbye after Simone has already walked away, because that’s her accepting the truth, accepting that her sister doesn’t want to be home and isn’t going to go home, and she might not know her anymore after this moment, and just being at peace with that.

“I think Devon goes back a really different person,” she continues. “You see a huge evolution with her. And I do think that when she goes home, she won’t drink anymore. I don’t think she sees Ray [Josh Segarra] as Ray anymore. I like to think that she gets herself together a bit, and leaves with more self-respect than she arrived with. Even though she stays and ultimately is stuck taking care of Dad, she’s actively made her choice now, and there is power in that for her.”

Although the story of “Sirens” feels complete — and is being marketed as a limited series by Netflix — Fahy says she’d be game to tell more stories in that universe.

“it ends in a very natural way, but I can imagine what the characters’ worlds become,” she says. “I, for one, would love to know what happens to Michaela, where she goes. So I think it’s definitely within the realm of possibility. We didn’t talk about it on set, but I would love to do more.”