Now, I will preface this and say that if I were in similar circumstances, with similar company, I would have probably freaked out as well, but maaaaaan, Lambert is one scary lady rockin cowboy boots. I have a few theories in this rambling "stream of consciousness" of mine. Please feel free to agree and disagree as you see fit.
I will say that I did like how most of the crew didn't too much care for each other, and that added a layer of suspense. It seemed like out of the "officer" crew, Lambert complained the absolute most. Even before the Xenomorph stepped in their lives, one of Lambert's first lines were her whining "I'm cold!" to a crew who were too busy stuffing their faces to pay much attention to her.
Being the navigator, Lambert would have known their position. She let Kane, Dallas, and Ripley know that they weren't in the Sol system, but instead a complete alien (pardon the pun) system; Zeta II Reticuli. Nobody paid any attention to her, before she became a smart ass and repeated herself: "It's not our system..."
It also seemed that she had some beef with Ripley even before Ripley wouldn't let Kane back on the ship. I think she just used the whole Kane incident to fully let her contempt towards Ripley play out in a public fashion. When they were going to get a landing party together, Lambert was uncongenial on being volunteered. She rolled her eyes a bit and said "Swell" while extinguishing her cigarette in disgust.
In one theory of mine, I think Parker and Lambert had something going on behind the scenes. It wasn't a love, but more of a....I don't know....friends with benefits kinda thing? I know that the entire ship were switching out sexual partners, but Parker made an overture directed at Lambert. She didn't act offended, she wasn't disgusted, she just kinda laughed. Let's not forget he sacrificed himself to save her. I honestly don't think he would have done that for anyone else on the Nostromo, maybe save for Brett. He just seemed very protective of her, especially after Ash revealed himself to be an Android.
When s**t started going down, Lambert was the first one to start freaking out. As soon as Brett bit the dust, Lambert was inconsolable. For some odd reason, the Nostromo crew put her on the motion tracker. Yes. The person who is cracking up and is starting to lose their cool is now basically in charge of someone else's life. So Dallas goes into the air ducts of the ship. The alien is stalking him, and Lambert starts blurting out directions to Dallas. Though Dallas never lost his cool throughout this whole affair, you could tell he was shaken in the moments leading up to his death.
I think Lambert felt somehow responsible after Dallas' death, and she completely shut down mentally. I wonder if she felt that it should have been Ripley who went into the air ducts instead of Dallas.
Another theory I have is that the Drone knew she was the most terrified of it. That's why it scared the living daylights out of her before it.....well, I'll get on that later. The other crew members were quite disturbed, but were able to hide it their encroaching fear: Dallas tried to think logically about the whole situation; Ripley was too busy being suspicious of Ash; Parker reacted with hate and anger towards the creature; Brett,well, I think he was just being Brett; and we all know about Ash.
She wanted to get the hell out of dodge, and I can't blame her.
Lambert was the most terrified of it, and maybe the Drone got some weird sense of ecstasy from the fear of its victims. Sort of like a biomechanical Pennywise, maybe the meat tasted much better when it was doused in fear.
Lambert's death scene is confusing, though ultimately satisfying. You don't really
know what happened to her, and that's what makes it better. After Parker unsuccessfully attempted to thwart the Drone's plans for Lambert, and Lambert not using that opportunity to escape, the alien focuses back on her. It seemed very curious in the crab-walking version of her death, but in the theatrical/DC version, the alien looked very sadistic and deliberate, as it was done toying around with her and ready to get down to business.
I am in the camp that believes the Drone had some nefarious plans for her, and those may or may not have included rape. I think the alien attacked her, maybe assaulted her, and then attempted to steal away with her. I believe it tried to go into a vent, but Lambert's whole body couldn't fit, so the alien
made her fit. What happened to the rest of her body up to interpretation. It's probably in the egg chamber.
I am probably going to purchase the NECA Lambert figure and the Drone and have it scare the sh*t outta her and put it on YouTube. I just wish NECA had released a Lambert with her regular Nostromo shirt and cowboy boots.