Alien (1979)

Directed by Ridley Scott
the following contains spoilers.

WHAT I WAS EXPECTING

Space explorers find aliens, aliens try and kills space explores. Space explorers return to the science center on earth but one of the creatures is living inside one of the astronauts and rips through his chest. Astronauts and scientists have to stop the Aliens from reproducing, breaking out of the science center, and infecting earth. They must not be entirely successful because many sequels follow.

In space no one can hear you complain about Prometheus

Blade Runner (1982)

1992 Director's Cut
Directed by Ridley Scott

the following contains spoilers.

WHAT I WAS EXPECTING
In the future, Harrison Ford is a detective. There are flying cars and video-screen billboards on sky scrapers. Everyone behaves like they are in an old-timey 1940s film noir. The detective is caught up in a case involving very life-like robots. As he investigates, he encounters fetching femme fatales and has run ins with spiky-haired punks in seedy Asian bars. Harrison Ford is probably a robot too but it's ambiguous.

Starring Harrison Ford, Sean Young and Harrison Ford's gun wielding twin

Aliens (1986)

Directed by James Cameron

the following contains spoilers.

WHAT I WAS EXPECTING
I watched this back-to-back with Alien so before seeing either I figured that the aliens from the first film, while temporarily defeated, continued reproducing at an alarming rate and have made the earth cold, dark and extra slimy. It's up to Ripley (Sigorney Weaver) to kick some extraterrestrial butt with her gritty strong-willed determination and oversize weapons.

Everything I know about the plot I guessed from this poster