One of the great delights of “Avengers: Age of Ultron” is the way the movie pokes at our assumptions about what’s happening when a man and a woman appear close on-screen. It was clear that there was something more than mere camaraderie between Natasha and Clint Barton (Jeremy Renner) in “The Avengers.” When she went to visit Loki (Tom Hiddleston) in an attempt to figure out what he’d done to the brainwashed Barton, the Asgardian trickster jumped to the logical conclusion: “Is this love, Agent Romanoff?” “Love is for children,” Natasha told him coldly. “I owe him a debt.”

It was a response that left room for her to be in denial, but “Avengers: Age of Ultron” revealed something rather more subversive, at least by the standards of contemporary filmmaking: Natasha and Clint are what they say they are, not soulmates in denial but the best of friends. And Natasha’s close to Clint’s wife, Laura (Linda Cardellini), too: “How’s little Natasha?” she asks Laura when they arrive at Clint’s house. “Actually, he’s Nathaniel,” Laura confesses. “Traitor,” Natasha whispers to the baby. In a few efficient lines, Whedon’s sketched in a warmer side of Natasha’s personality. It’s not that it didn’t exist before; it’s just that, until the trip to the Bartons’ farm, she wasn’t around the people who deserved to see it.

Later, as she and Clint weave through the ruins of Sokovia, they diffuse their nerves by talking about Clint’s latest idea for a home renovation, a plan to turn his dining room into a workspace for Laura. “You guys always eat in the kitchen anyway,” Natasha tells him, cool as the world is falling away beneath them. There’s a subtle but profound intimacy to the exchange: It’s proof of how well they know each other, how much comfort they take from each other, how well Natasha is integrated into Clint and Laura’s lives.