In an interview with Variety, show creator Molly Smith Metzler explained that "hey hey" -- a phrase frequently exchanged between Julianne Moore's Michaela "Kiki" Kell and Milly Alcock's Simone DeWitt throughout the Netflix limited series -- was inspired by her summers working at the Yacht Club on Martha's Vineyard.
"I had noticed that they picked up each other's way of saying things," Metzler said. "One woman would come in with a new bracelet that just dropped in town, and then they'd all have it."
"They did it with language, too, they had their own way of speaking and there was a contagion to it," she continued. "In my mind, Michaela just sort of said it one day, and then Simone said it back, and it became something the two of them say. I just made it up."
Metzler also explained the meaning behind the locket Michaela wears and gifts to her friends -- and "no, there's no drugs" in them, she said.
"The lockets are a real thing in Nantucket Island," Metzler said. "It's something you can only buy in Nantucket, they're called basket necklaces, and they usually have ivory from Wales in them. But they're very expensive, they're handmade, and everyone in Nantucket and Martha's Vineyard is wearing them."
Metzler said that the necklaces are very much a "status symbol."
"You're not in the club if you don't have one," she said. "[Costume designer] Carolyn Duncan made that happen, made all of them happen. It's a great symbol of having arrived. You have the key, you have the necklace, but it's a little culty. It's a little like wearing a cross, like a religion. You know something that everyone else doesn't."
From her time spent in Martha's Vineyard and Nantucket, Metzler knew she had to include Lilly Pulitzer-inspired designs in the series.
"Lilly Pulitzer is for real," she said. "They all have it on in Nantucket. Then there's the Nantucket reds, the salmon color pants. The first time you see it, you're like, 'Where am I?' It's so bright. It's sort of like, if you've been there, you're in on the joke, you know the pants to buy. It also takes a certain status to put on a dress like the one Simone has on when we meet her.
Sirens, which premiered on May 22, is based on Metzler's play Elemeno Pea and follows Devon (Meghann Fahy) as she sets off for the picturesque beach estate where her sister Simone works for billionaire Michaela after their father is diagnosed with dementia.
When she arrives on the island, Devon becomes increasingly concerned about Simone's creepy relationship with Michaela, and Michaela's cult-like way of operating her estate.
"The vibrancy of this world: the cliff, the island, all those visual elements, it was extraordinary to be able to bring them to life," Metzler said. "It's one thing to hear about that on stage, but we don't get to see it in person. Everything got wider, deeper, more layered, more lush, more pastel, more cult."