Sink isn’t completely unknowable, of course. Her friends, family, and colleagues help paint a fuller picture of what she’s like in her off-hours.
From her brother, actor Mitchell Sink, I learn about their childhood in Texas, where they’d put on scenes of High School Musical and Wicked for their family. Their dreams of Broadway were so big that their parents moved the entire family to the New York City area to support the pursuit.
“She’s so driven, so focused, and super passionate about everything she does,” he says. “But at the end of the day, she’s my sister, and she’s very silly, very goofy, and ridiculous. Seeing both sides of that is really fun.”
Of her temperament, Gaten Matarazzo, who plays Dustin on Stranger Things, said, “There’s an initial assumption that she might be introverted, but she’s an absolute blast in group settings.”
The two have known each other since childhood, when they were on Broadway at the same time alongside Mitchell and their Stranger Things costar Caleb McLaughlin. Matarazzo doesn’t remember their first meeting but thinks it was probably on the playground where all the theatre kids would hang out between shows. “She’s always felt older than her age,” he says. “Anytime I was around her, I was like, Oh, she’s such a good hang; she’s so chill. But also, I’ve got to get my shit together; she seems so put-together.”
On her transition into cinema, Oscar-winning actor and star of the 2025 comedy-drama Rental Family, Brendan Fraser was similarly struck by her maturity from their first meeting; he played Sink’s father in The Whale. “She’s got impeccable timing as an actress and talent, clearly, in spades. I won’t speak for her—she may or may not concur about that because she’s humble—but I know that she never gets comfortable. She’s honing her craft take by take, and gets better the more that she plays a scene.”
The best insight into who Sink is—besides Sink herself—might come from her castmate, close friend, and sometime roommate Maya Hawke. The two lived together in Atlanta while filming the last two seasons of Stranger Things, which returns for its final chapter on 26 November. They spent their free time doing “grandmotherly activities,” says Hawke, such as making big pots of soup and stews together, discussing the best kinds of gluten-free bread, watching Modern Family as they knit and crocheted curled up on the couch, and taking walks to the yarn store.
“She’s thoughtful and intentional,” Hawke says. “She takes her time with people and gets to know them. And when you get over that line with Sadie, it’s the warmest, most delightful, funny, goofy, cuddly, supportive, generous, tricky, smart, clever, makes-you-laugh-until-you-cry, curled-up-on-the-carpet-in-front-of-a-fireplace feeling. There’s a real specialness to that because she doesn’t show that part of herself to everybody.”