David & Roy Batty

Most probably a "Like father like son" scenario,. Weyland is an a$$hole and raised david as his son so it's no wonder David is a passive-aggressive little jerk.

In my opinion, after seeing today's viral ("10-11-12") it's more about the concepts stated in Nietzsche's books, especially "Also Sprach Zaratustra". Both guys, Roy and David, are "like-humans", but without morality. Perfect cognitive abilities, bodies of more strentgh and durability, etc. But no moral issues (as stated in a viral with David8). And this reminds me the sentence of Ash form "Alien" - about the Xeno and its "perfection". Saying this again, in my opinion the key is in Nietzsche's work.