Ridley Scott's Prometheus is a movie that catches a lot of flack. Admittedly, some of it is well deserved. Seriously, it has the dumbest characters with the worst decision-making skills ever put on screen. As a precursor to the Alien movies, it obviously doesn't live up to the (possibly unfair) expectations piled upon it before release. People were hoping for something epic and game changing to the point where anything less would have been a disappointment. And guess what? It ain't perfect, not by a long shot. But that doesn't mean it's completely without redeeming qualities.
Scott has said that while Prometheus isn't a prequel to Alien, and there may not necessarily be a causal link between the two, it does exist in that world, and the ties between the two are strong indeed. This film may take place much earlier on the timeline than the previous films, but throughout, Scott weaves in countless allusions and references to Alien, the horrifying xenomorphs, and elements that we know will come into play in the future. In this way, Prometheus sets the stage for Ellen Ripley, the Colonial Marines, and the action that is to follow. Much of that happens at the end of the film, and is definitely worth talking about moving forward. Let's talk about how the end of Prometheus connects to Alien:
Birth Of A Facehugger
Springing from the twisted mind of Swiss surrealist H.R. Giger, the xenomorphs -- the heinous, armor-plated killing machines that populate the various Alien films -- rank among the most horrifying movie monsters of all time. But the first extraterrestrial presence we meet, however, are the facehuggers. You know, the nasty little buggers that latch on to your face and impregnate you with a xenomorph that, after a proper incubation period, will ultimately burst out of your chest and kill you.
In Prometheus, we witness what appears to be the birth of the first such facehugger, also known as a Trilobite. It's a roundabout process, to be sure, but the creature's origins lie here. When the crew of the Weyland Corporation (not Weyland-Yutani yet, but we'll get to that) ship Prometheus lands on the moon LV-223, one of the many things they find is a room full of "vases," which closely resemble the rooms full of eggs from the earlier movies, the very same eggs that hatch the facehuggers. But we still have a few evolutionary steps to go.
The nefarious robot David (Michael Fassbender) takes the viscous black substance he finds in these vases and slips a dose to Dr. Charlie Holloway (Logan Marshall-Green). It's unclear whose orders David follows, but he is the one who may be responsible for jumpstarting the xenomorph evolution. This scenario, as you probably remember, does not go particularly well for ol' Charlie, as it messes with his body something awful. Before he winds up burned to a crisp, he has sex with Dr. Elizabeth Shaw (Noomi Rapace), which is impressive because she was previously unable to conceive.
Whatever the result, the fetus is not human, it's some sort of squiggly, human-alien hybrid monster, and when she cuts the rapidly gestating spawn out of her belly in the latter portion of the film, the creature may be the first facehugger. Initially, it looks like some sort of angry, demented space squid, but when it latches onto the Engineer---actually specifically when it dies and falls off of the Engineer---it is very obviously akin to the little buggers.
Physically it is much larger than previous facehuggers we have seen, and unlike the ones we've seen before, it kills the host, but the end result, as we see shortly after the credits role, is the same. How these changes happen is somewhat unclear, especially as they take place over a relatively short span, evolutionarily speaking---Prometheusis set around 2090, while Alien takes place in the year 2122. The implication is that, unless these creatures have an extra-fast evolutionary process, they had a helping hand. Perhaps it was the Engineers tinkering with something they didn't quite understand. But another likelihood is that Weyland-Yutani did their own genetic messing around. They've attempted to weaponize the xenomorphs, and they're certainly less that scrupulous in matters such as these.
With this link, Prometheus and Alien share similar psychological tropes that tap into primal fears about parenthood that have been used many times in horror. There's something unknown, uncontrollable growing inside of you. You worry about what happens if it's evil, and the possibility that what you create, what you birth, will ultimately kill you. This is especially heightened in Elizabeth's case, as with her earlier inability to conceive, whatever this is isn't natural.
For his part, David serves a similar purpose. At one point, Peter Weyland (Guy Pearce) says that the android is as close to a son as he has---though it's later revealed he has a daughter, Meredith Vickers (Charlize Theron)---and the robot is really the doom of his creators. These themes of killing your parents, literally and metaphorically, are all over Prometheus. The Engineers made weapons in order to destroy their own creation on Earth, which then got loose and killed them.
But the connection only starts with the facehuggers. Read on.