In myth, Prometheus makes man from clay, sides with the gods against the titans, and steals fire from the gods and gives it to man, only to be condemned for it. So, I suppose the "Prometheus" we see at the beginning of the film is part of one faction of engineers that creates and guides human life, against the will or law of their race, while the ones we see at the end of the film are part of another faction seeking to destroy their works. Their enemies. If the "good engineers" gave us fire, that is technology 2000 years ago, perhaps the "evil engineers" are out to destroy the perceived threat of us. Or maybe to them, all or them, Earth was just a petri dish that served its purpose, and now goes to decon.
Just a guess.
Oh, and A-. It was great.
That is a reasonable explanation. And I agree this is the best sci-fi flick IMO since Trek XI.
Regarding box office totals the film brought in $50 million in the US
And, worldwide its brought in $141 million
It cost Fox and estimated $130 million
to make the film and as pointed out 1/2 the cost The Avengers
However, Avengers is up to over $1 billion in box office receipts worldwide so at this point Prometheus has just barely paid for itself.
Comapring Prometheus to Avengers Assemble is not a fair comparrison.
Avengers Assemble is rate 12A in the UK (PG-13 in the states)
Prometheus is rated 15 in the UK and R in the states.
So in countries where the rating is absolute like the UK. No one under 15 is permitted entry to see it. You lose some audiance numbers.
It's true comparisson would be against other R rated films
NB: Figures are US Domestic only
I would expect Prometheus to come in at around the low US$300m mark. In worldwide takings.
Though intersting to see some films like "The Kings Speech" given an R in the US whilst it only got a 12A in the UK.
If anyones interested you can see the original BBFC classifcation report for "Alien" here