How we cite our quotes: All quotations are from Alien.
Quote #1
DALLAS: You get what you're contracted for just like everybody else.
BRETT: But everybody else gets more than us.
As soon as we're introduced to this community, it is clear that things are less Star Trek than Metropolis. Brett and Parker are clearly the "lower class citizens" of the Nostromo and receive less of a bonus than the rest of the crew.
Quote #2
PARKER: You ever notice how they never come down here? I mean, this is where the work is, right?
Parker's quote here squarely places Brett and him as a member of the "working class" while the rest of the crew would be the bourgeois administrators. It is very mini-Marxist aboard the Nostromo.
Quote #3
RIPLEY: Ash, that transmission, Mother's deciphered part of it. It doesn't look like an S.O.S.
ASH: What is it?
RIPLEY: It looks like a warning. I'm going to go out after them.
ASH: What's the point?
We've seen a lot of self-interested motivation when it comes to the crew of the Nostromo. Brett and Parker want their bonuses, and Kane's curiosity pushes the crew to continue on exploring. Here, for the first time, we see character acting for the good of the group rather than for herself. Sure, Ash stops her, but it's a start.