1979’s Alien is a horror movie about rape. Screenwriter Dan O’Bannon and his story partner (and roommate at the time) Ronald Shusett figured that out early in the scripting process. The life cycle of their alien monster was based on certain species of wasps that lay eggs in their prey, guaranteeing the host’s death when the wasp larvas hatch and chew their way to freedom. But according to O’Bannon in the television documentary The Alien Saga, he decided that the really uncomfortable idea he wanted to work with was “homosexual oral rape,” the one thing guaranteed to “make the men in the audience cross their legs.” In Ridley Scott’s original Alien, unlucky crew member Kane gets an alien ovipositor forced down his throat, becomes pregnant, and gives gory birth, dying in the process. It’s a twisted parody of a familiar life cycle—because the victim is a man.

The same reversal of traditional gender roles applied to Alien’s one survivor. Sigourney Weaver’s name-making role, Lt. Ellen Ripley, was already a strange female character for a 1979 movie. She’s cold, logical, and rule-bound rather than maternal or protective. She has no romantic or family ties. She isn’t willing to defer to the men around her, regardless of relative rank. And yet she’s the movie’s ultimate hero, destined not for narrative punishment or censure, but for hard-won victory at the end of the movie. And part of that came from the fact that O’Bannon’s original script called for the character (“Roby” at the time) to be a man, and that he didn’t significantly retool the character when her gender changed.

But Ripley isn’t even Alien’s least-feminine female figure: The ship’s computer, “Mother,” is an even colder and less comforting presence. From the beginning of the film, Mother is dismissive of her “children,” carrying them to a planet where they’ll take on an alien boarder and be killed one by one, and offering no help or comfort as they die. Mother’s programmed priority is to get an alien specimen home, not to care about or protect her human charges. In the end, Mother’s unsympathetic voice provides a countdown for Ripley, reminding her at every turn that her ship is about to blow up, and Ripley has to leave the womb or die.

This is the world James Cameron inherited when he wrote and directed the 1986 sequel Aliens: a gender-swapped world where men have horrible babies (the android Ash even quietly refers to Kane’s emerged parasite as his “son”) and women are creatures of implacable logic and sudden violence. And it’s a world where all marks of gender, all indications of sexuality, are re-interpreted as threats: H.R. Giger’s design for the alien threats openly gives their parasite stage and adult forms phalluses for heads (with smaller phalluses in their mouths for sudden, explosive penetration), and turns their lairs into dripping fallopian-tube tunnels full of vulval doorways.

There’s no end to the psychological interpretations of the Alien movies. They’re rich enough in Fruedian and Jungian imagery to fund a pocket industry of people dissecting how, say, the male-pregnancy plot reflected America’s preoccupation with legal abortion and reproductive rights in the 1970s, in the immediate wake of Roe V. Wade. Or how Ripley’s development over the decades shows different preconceptions of women and their evolving roles in America. Cameron inherited a thematically rich environment and a highly successful horror feature. The question was how to respect it and build on it without falling into the usual horror-sequel traps.

Part of his solution involved switching tonal gears, embracing action as well as horror. He also found ways to open Alien’s world by bringing in more characters, ships, and weapons—and in the end, a new alien life stage—instead of by piling on exposition and explanation. And his script deepens Ripley by giving her something to care about besides her own survival, and by taking her back to a more traditional feminine role, as a caring maternal figure.

But he does all this without dismissing or disregarding what worked about Scott’s Alien. Even in a bigger world full of heavy weapons and crowds of space Marines, there’s still plenty of time for Alien-style isolation and quiet dread. And even the maternal version of Ripley is still a blunt, decisive leader, not sentimental or soft. She isn’t inhuman: If anything, she’s more empathetic toward other people in Aliens, clutching her own chest in sympathy pain when she sees a chestburster emerge from a colonist’s chest, and vicariously feeling the deaths of the canon-fodder Marines even more than their hapless, helpless commanding officer does. But Cameron doesn’t let her emotions get in the way of her determination. He sticks by the established character, adding to her instead of subtracting from her. And he pulls the same trick with the rest of the world. Aliens takes the usual sequel route of creating a bigger, faster world than the first movie. But it’s still recognizably the same story, with the same concerns and the same people.

Aliens starts 57 years after Alien, as Ripley’s escape pod is found and opened by a salvage crew, which sends her back to the Weyland-Yutani company that employed her in the original film. When she tells her story, she’s dismissed by the company’s bean-counters, with a sense that they’re writing her off as a classic female hysteric, jumping at shadows. But behind her back, the company—this time in the form of sleazy ladder-climber Carter Burke (Paul Reiser)—makes the exact same mistake it made in Alien (and makes over and over throughout the franchise): It tries to control and profit from the aliens. A group of terraforming colonists has landed on the planetoid where Ripley’s crew originally encountered their alien, and Burke sends them to investigate the infected downed vessel Ripley’s crew explored.

Before long, the terraforming crew goes silent, and Weyland-Yutani sends in the space Marines to see what happened. Ripley is reluctant to go back to the planetoid, but feels a need to face and master her nightmares. And she does, completing her transformation from reluctant horror-movie Final Girl to what’s widely considered the first full-on female action heroine. And all it takes is a bond between her and the colony’s sole survivor: a little girl named Newt (Carrie Henn).

The extended “special edition” cut of Aliens has been widely dismissed as inferior to the tighter (though still 137-minute) theatrical cut, but it does feature one scene that probably shouldn’t have been left on the cutting-room floor: the sequence where Ripley learns her own daughter has grown up, married, aged, and died during the 57-year period where Ripley was in suspended animation in her capsule. It helps explain why Ripley is affected so strongly when she meets Newt, and why she’s so readily able to shift gears from protecting herself to protecting a stranger.

But even without that scene, it’s clear enough that Cameron’s film has moved the emphasis from exploding unnatural fathers and cold wire mothers to warmer family relationships. In the process, he gave the Alien franchise its first spark of emotional connection in a vast, uncaring, murderous universe. Newt follows her own arc throughout the film, from deeply traumatized, near-feral animal-child to a little girl who’s learning to trust the world again. And the moment when she embraces Ripley and calls her “Mommy” is as sweet a moment as the Alien franchise can muster. The subsequent films continue to be obsessed with artificial and unnatural motherhood, from Ripley embracing her chest-bursting offspring at the end of Alien 3 to her faux-nurturing relationship with the hybrid in Alien: Resurrection. But for a moment in Aliens, Cameron allows the series one tender mother-child moment, one parental relationship that isn’t compromised by half of the equation murdering the other half.

Aliens does keep motherhood creepy, though. Cameron’s alien queen is introduced as a bloated monstrosity giving birth to egg after egg in a twitchy, slimy spasm of creation. Aliens is often billed as a pure action movie that steps far away from Alien’s more traditional horror, but the scene where Ripley and Newt first encounter the queen is the most frightening and atmospheric sequence in the entire series. Cameron directs it without dialogue, without music, and with minimal sound effects. It’s a moment of understanding, first for Ripley—as she sees that she and Newt have run from one threat into a bigger one—and then for the audience, as Cameron definitively proves that the Alien-series aliens aren’t just animals, as many of the film’s characters repeatedly claim. The alien queen recognizes Ripley’s threat, when she mimes her intention to burn the queen’s eggs. The queen is capable not just of rational thought, but rational response: She clearly instructs her drones to back away from Ripley and Newt, in order to protect the eggs—and they clearly understand and obey. The queen is even capable of vengeful rage, as Ripley burns the eggs anyway. (While the moment where Ripley takes in the queen’s bulk is the series’ scariest, the shot where she reacts to the opening facehugger egg by cocking her head at the queen, as if to say, “Really? That’s how you want to play this?” is probably its wryest.)

Aliens openly comes down to a showdown between mothers: one protecting her adoptive daughter, the other avenging her slaughtered brood. It’s not too hard to see an alternate-universe take where the alien queen is the wronged one: She’s finally settled down and raised a family of her own, when this interloper bursts into her home and kills her children, so she chases the murderer down. That sounds facetious, but the queen’s pursuit of Ripley closely mirrors some familiar last-ditch action-hero behavior—including grabbing onto the skids of the villain’s escaping ship and flying off with them to continue the fight, like Jason Statham in Crank or Melissa McCarthy in Spy. The queen alien is a monster, but Cameron also clearly identifies with her just a bit, as a ferocious protective force, the maternal instinct run wild. Even Ripley recognizes she’s dealing with another mom: Her first instinct when she faces the queen is to manipulate her by threatening her children, and when she moves to protect Newt, snarling, “Get away from her, you bitch!” she’s talking, not to an unthinking thing or a gender-neutral creature, but to something she identifies as female.

Looking back at Aliens from a vantage point nearly 30 years later, when we’re still constantly struggling with the representation of women in entertainment, Ripley seems like a turning point, a watershed for tough heroines who can hold their own with the boys. (She isn’t alone in the film, either; Aliens gave audiences a casually competent female spaceship pilot and a female Marine who’s tougher than the boys. If Aliens came out today, there’d be no end of MRA backlash and thoughtful thinkpieces about Vasquez, who not only verbally abuses and undercuts her male counterparts, but gets fulsome praise from the rest of her unit every time she gets off a castrating quip.) And she was certainly unusual for her time, to a degree that critics didn’t entirely embrace. (Walter Goodman’s 1986 New York Times review of Aliens, sneering about Ripley: “Believe it or not, this smart good looker is a one-woman army. There is something inherently parodic about Warrant Officer Ripley, in a T-shirt, blasting away with a flame-spouting, grenade-launching weapon capable of wiping out a small zoo; it’s a Rambo joke. But Miss Weaver does the job without cracking a smile.”)

But Ripley isn’t just a woman Rambo, or a Strong Female Character prototype, or a feminist icon. She’s a sideways step for the Alien series, away from the terror mined out of a rape narrative and enforced pregnancy, and toward the series’ one comforting, supportive, surviving familial relationship. Alien skews sex and childbirth into terror territory by making it something unnatural and unsupportable. With Aliens, Cameron gave the story plenty of excitement to go along with the dread. But he also turned a rape story into a motherhood narrative, and found emotional attachments even in Alien’s darkest and most chitinous elements. There’s a reason Aliens is often praised as one of the few sequels to surpass its predecessor. It maintains a world of bottomless fear, but finds love in it somewhere as well.

Movie Of The Week coverage of Aliens continues on Thursday, with Keith and Scott discussing Aliens’ storytelling style and its relationship to the original film. Genevieve Valentine will also chime in on Thursday, with a look at the film’s groundbreaking ensemble cast and how it defined action-movie ensembles going forward. And just incidentally, remember, there’s no universal right age to watch Aliens for the first time.