It's been over two decades since writer/director Luc Besson’s Léon: The Professional hit theaters, and we’re willing to bet that you’ve yet to shake off how the movie made you feel. The crime thriller that launched Natalie Portman’s career, and put French actor Jean Reno front and center in Hollywood, Léon tells the story of a professional assassin who takes in his pre-teen neighbor after her family is murdered. The two then develop a friendship so close that you might still find yourself fearing it could cross the line of appropriateness (even if you've seen the film 100 times and breathed a sigh of relief at its outcome). With its boundary-pushing plot and expert direction, the film is widely (and rightly) regarded as one of Besson’s best works.

1. NATALIE PORTMAN’S PARENTS WERE COMPLETELY AGAINST HER PLAYING MATHILDA.

It was an extremely complicated role for an 11-year-old: Not only would she have to deal with a broken home and violence, but she’d also have to deal with the unwanted sexualization of a young girl. In Starting Young, a documentary about Portman that’s included on the 10th anniversary DVD edition of Léon, the actress admits that after she read the script, she was so moved to tears by the film that she knew she had to have the role. Her parents weren’t as convinced. “My parents were like, ‘There is no way you’re doing this movie. This is absolutely inappropriate for a child your age ... and I was like, ‘This is the greatest thing I’ve ever read! You’re gonna ruin my life!’” she shares in the doc. “[I] was basically just fighting with them so much.”

2. IN THE ORIGINAL SCRIPT, LÉON ACCIDENTALLY WALKS IN ON MATHILDA WHILE SHE'S IN THE SHOWER.

Portman’s parents were understandably not comfortable with this scene. In Starting Young, Portman notes that her parents scaled the sexual undertones way back. It was a point they made sure to detail in their daughter’s contract.

3. RENO AND PORTMAN WEREN’T ALLOWED TO REHEARSE THE FILM’S MOST CONTROVERSIAL SCENE, WHERE MATHILDA PUTS ON A DRESS GIVEN TO HER BY LÉON.

Up until the moment of the dress scene—which was deleted in the original U.S. theatrical version for its racy content (it would be restored a decade later)—it’s easy to believe that Léon acts as a person stuck between childhood and adult male. It isn’t until this turning point that one begins to worry. Here, Mathilda makes Léon tell her he likes her dress and whispers to him the importance of a girl’s first time having sex. He rejects her advances, but the tension is evident in his expression.

As Reno puts it in the film’s DVD commentary, it’s “the beginning of the perversity.” Reno often asked the director when they would read the part, and Besson would avoid the question. Not being able to read the scene helped Besson and his cast genuinely capture the awkwardness the characters felt at that moment. “[Léon and Mathilda’s] relationship was very connected and very strange,” Reno concluded.

4. PORTMAN’S PARENTS ARE THE REASON WHY MATHILDA QUITS SMOKING IN THE FILM.

As per the agreement Portman’s parents outlined with Besson, the actress was allowed five fake cigarettes in her hand during the entire film shoot, and she was never allowed to inhale a single one of them. If you pay close attention to her character, you'll see that she only puts the cigarette to her lips, but never blows smoke out. Additionally, her parents demanded that her character quit smoking at some point in the movie. In the film, Léon scolds Mathilda for smoking, and later you see her throwing her unfinished cigarette away when she’s alone.

5. PORTMAN’S MARILYN MONROE IMPRESSION IN THE FILM WAS INSPIRED BY MIKE MYERS.

During her audition, Besson asked Portman if she could do any celebrity impressions; what you see in the film is the entire arsenal that she presented to the director. While she was obsessed with Gene Kelly and Madonna as a kid, her Marilyn Monroe impression was done without having seen any of the legendary bombshell’s work. “I had never seen the original Marilyn tapes at all,” Portman says in Starting Young. She goes on to admit that her impression was informed by a vague memory of Mike Myers impersonating Monroe in Wayne’s World.

6. BESSON GOT THE IDEA FOR LÉON WHILE WORKING ON LA FEMME NIKITA.

In the 1990 film La Femme Nikita, Reno plays Victor the Cleaner, an operative sent in to salvage Nikita’s botched mission. According to the DVD commentary, Besson was so inspired to explore Reno’s character further that he developed a story around him, which became Léon. Fortunately (in retrospect) for the director, when filming of The Fifth Element was delayed due to Bruce Willis’s schedule, Besson was afforded the time to shoot The Professional as a passion project.

7. THE CHELSEA HOTEL WAS USED FOR THE INTERIOR SHOTS OF MATHILDA AND LÉON’S APARTMENT BUILDING.

Léon and Mathilda’s apartment building might look like a place where burnouts escape to cook some meth, but the spot is actually an iconic part of New York City history. The Chelsea Hotel was once a place where Allen Ginsberg and Gregory Corso enjoyed philosophical exchanges; Bob Dylan, Janis Joplin, Charles Bukowski, Tom Waits, Patti Smith, Leonard Cohen, and Iggy Pop all called it home; Arthur C. Clarke wrote 2001: A Space Odyssey while staying there; Andy Warhol filmed Chelsea Girls within its walls; and Sid Vicious’s girlfriend, Nancy Spungen, was found stabbed to death there (leading to Vicious’s arrest).

8. THE CITY OF NEW YORK INSPIRED THE FILM.

While the film was shot in both Paris and New York City, Besson has noted that Léon is first and foremost a New York movie. “When it comes to Léon I feel comfortable in New York because for me, in New York, you can be invisible. You can see someone lying on the street and no one will stop,” Besson told Stumped Magazine. “If you have no phone and no credit cards, no one knows where you are … One more thing: you can’t shoot Léon in France because in France in every building you have a concierge and she knows everything. She is glue with the police all the time so you can’t be invisible in Paris.”

9. GARY OLDMAN’S CLASSIC DELIVERY OF THE LINE “BRING ME EVERYONE!” WAS PURPOSELY MEANT TO MAKE LUC BESSON LAUGH.

Never one to under-serve his characters, Gary Oldman—as Stansfield, the film’s drug-addicted DEA agent antagonist—gave Besson everything he had, creating one of the most memorable (and now classic) moments of the film. “What’s funny is that the line was a joke and now it’s become iconic,” Oldman told Playboy. “I just did it one take to make the director, Luc Besson, laugh. The previous takes, I’d just gone, ‘Bring me everyone,’ in a regular voice. But then I cued the sound guy to slip off his headphones, and I shouted as loud as I could. That’s the one they kept in the movie. When people approach me on the street, that’s the line they most often say.”

10. BESSON HAS SHUT DOWN RUMORS THAT A SEQUEL IS IN THE WORKS.

So stop asking. During his press tour for Lucy, Besson told The Guardian, "You can't imagine how many people ask me for a Léon sequel. Everywhere I go they ask me. If I was motivated by money, I would have done it a long time ago. But I don't feel it."

In an earlier interview with Cinema Blend, Besson elaborated on the topic, saying, “Natalie is old now, she's a mother … It's too late. If I got an idea tomorrow about a sequel, of course I would do it. But I never came up with something strong enough. I don't want to do sequels for money; I want to do a sequel because it's worth it. I want it to be as good or better than the original."

11. JEAN RENO PLAYED LÉON AS EMOTIONALLY REPRESSED TO MAKE SURE THE AUDIENCE KNEW HE HAD NO SEXUAL DESIRE FOR MATHILDA.

In the DVD commentary, Reno says he made a conscious decision to make Léon a little slow so that he didn’t come off as physically threatening to Portman’s character. “[Léon is] somebody who’s lost his parents, an immigrant, in fact ... If you’re not smart, it means no brain, means not a lot of words, so you have to put a lot of emotions. You defend yourself in that way, the instinctive,” Reno says about portraying Léon. “If you’re slow, [Mathilda] will control the situation."