In Todd Haynes’ new film, “May December,” Joe Yoo raises monarch butterflies at the house he shares with his wife, Gracie Atherton-Yoo, whom he met two decades earlier while working at a pet store when he was 13. Gracie, his boss, was an adult with kids his age. They now have three adult children of their own, the last two of whom are about to move out for college. Joe’s insects are all he has left.

The butterflies are a metaphor. (Aren’t they always?) Joe (Charles Melton) tends to them with the level of care he didn’t receive, instead abused from a young age and prematurely granted adult responsibilities when his kids were born during his teenage years. Gracie (Julianne Moore) relies on Joe for emotional stability, curbing his ability to prioritize his needs. He is a 36-year-old man trapped in a cocoon.

Now streaming on Netflix, “May December” is loosely based on mid-1990s tabloid fixture Mary Kay Letourneau, a middle school teacher who was arrested after beginning a sexual relationship with her adolescent student, Vili Fualaau. Like Letourneau, Gracie was sent to prison, where she gave birth to Joe’s eldest child. After her release, she registered as a sex offender in Georgia and married the now-young man, just as Letourneau did in Washington state.

By revisiting events once treated as salacious tabloid fodder, Haynes critiques a culture that struggled to consider that an impressionable teenage boy could also be a victim of abuse. Haynes highlights that voyeurism by approaching the story through the entirely fictional character Elizabeth Berry (Natalie Portman), an actress set to play Gracie in an upcoming biopic. Elizabeth embarks on a research trip to the Atherton-Yoo household, where the two women engage in a psychological pas de deux. And yet it is Joe who ends up discovering the most when Elizabeth’s prodding forces him to realize the disturbing tragedy of his situation.

Melton, 32, who played Reggie Mantle in the CW’s Archie Comics drama series “Riverdale,” said in an interview with The Washington Post that he jumped at the chance to work with Haynes and his lauded co-stars. He approached what he called the “beautiful blueprint” of Samy Burch’s screenplay with empathy for Joe, drawing parallels between the character’s great sense of obligation toward his family and the actor’s own duties. When Melton was a preteen, he recalled, his father gave him an “inspirational speech about responsibility and taking care of my mother and two sisters.”

“As a kid, when your dad is telling you that, you can’t help but put on those shoes that are too big for you in the moment, hoping that one day you will grow into them,” Melton said.

“May December” is not a subtle film. Haynes borrows bits of a melodramatic piano score from the 1971 film “The Go-Between,” a jarring choice that underscores the ludicrous nature of treating a story like Gracie and Joe’s — or Letourneau and Fualaau’s — as entertainment. The film grants Joe a level of compassion his real-life counterpart didn’t always receive, making it clear that, in many ways, Joe is still frozen at the age he was when Gracie began to abuse him.

He observes his caterpillars with a childlike fascination, whereas Gracie expresses disgust over the sight of her husband’s “bugs.” Her apathy is striking. And yet, like Fualaau, who publicly refused to see himself as a victim, Joe insists to Elizabeth that he doesn’t want to be seen as a lifelong victim, either. As an adult, he chooses to stay with Gracie and sticks around to raise their children. He believes in the truth of their romantic love, and the beauty of the family they created together. A scene in which he tears up while smoking his first-ever blunt with his teenage son, Charlie (Gabriel Chung) — while blubbering to Charlie about how proud he is of him — captures the dichotomy of Joe’s fast-tracked maturity and stunted youth.

“There’s a weight that Joe carries, this repressed feeling he’s internalizing,” Melton said.

The film marks Chung’s first acting credit. Melton took Chung and the other actors playing his character’s children (Elizabeth Yu and Piper Curda) under his wing, inviting them to watch movies and do laundry at the home where he stayed while they shot in Savannah. “Building that relationship also helped me inform Joe’s experience as a father,” Melton said. “He’s almost like a friend-dad, in a way. A dad who wants to connect with his kids but seems so far away.”

While preparing for the role, Melton sought inspiration from Tony Leung’s performance in “In the Mood for Love” (2000), and noted how Wong Kar-wai’s films are imbued with “so much pathos, so much quietness, so much expression while saying so little.” He thought back to Heath Ledger in “Brokeback Mountain,” Ang Lee’s 2005 film about two cowboys who share a forbidden romance.

Like Ledger, whose soulful eyes betrayed his “Brokeback” character’s reticence, Melton’s performance is very physical. The actor stands significantly taller than Moore and Portman, but shrinks in their presence on-screen. With his hunched shoulders and awkward movements, Joe carries himself like an overgrown child. “That really came from the internal work,” Melton said of his process. “There’s so much source material we can draw from as actors. ... Part of that process is eliminating the judgment and not having formulated opinions. Coming at it from a place of empathy.”

When Joe’s sense of self begins to shift, so too does his physicality. At a pivotal moment in the film, Joe asks Gracie — seemingly for the first time — whether he was “too young” to consent to their relationship. She explodes, insisting he pursued her and held more power. “Who was in charge?” she repeatedly demands to her distraught husband. But this time, he doesn’t shrink back. (Worth noting: Fualaau and Letourneau legally separated in 2019, after more than 14 years of marriage.)

“It’s so beautiful because it’s the first time we really see Joe breaking from that cocoon of arrested development — that adolescence — where he’s trepidatiously acknowledging the question,” Melton said. “‘What if I was too young? What if?’ Something that may have been repressed for so long.”