In Prometheus we see the awakened Engineer standing up and apparently bowing in front of the humans that he kills minutes later.
Was that a sign of respect or was he just feeling sick after standing up quickly? If it was a sign of respect, how do you explain his later behavior? Did something suddenly cause him to change his initial opinion? (like David's question, for example)
I'm referring to the version of the movie available on iTunes. In this version the Engineer stands completely upright and only then bows. It doesn't look like the alternate scene videos on YouTube where he leans too far forward while raising from the bed.