One thing I always think about when I watch this movie...Ripley?
She's been in cryo-sleep for 57 years, wakes up to find out that her daughter has died...the lady has nothing at all...nobody. She's completely alone in a world that's likely changed drastically since she went to sleep, with no loved ones, friends...literally everyone is a stranger. Its hard to imagine that kind of loneliness, I think.
And if it weren't for this expedition...where could she have gone, what could she have done with herself? Her previous life is over...she's got no home, no job...the only thing she has now is this group of people she's been assigned to consult...and they've already bonded with each other through previous missions, battles or whatever.
Its no wonder she was willing to risk her life for Newt...she had nothing else to live for, really.
Anyway, just kind of a weird exercise in bleakness, trying to imagine how alone she must have felt, its a very unnatural state to be in.