How did it come to be that Deckard
often considered to be a replicant
started hunting replicants?
How did it come to be that Deckard
often considered to be a replicant
started hunting replicants?
Depending on whether you subscribe to the idea of Deckard being a replicant or not, the story revolves around Deckard being a retired cop with an "aptitude" for ferreting out replicants on the run.
Deckard, whose job as a "Blade Runner" was to track down bioengineered beings known as replicants and "retire" them ("retire" being the official term for the killing of replicants), is told by Bryant that several have escaped and come to Earth illegally. As Tyrell Corporation Nexus-6 models, they have only a four-year lifespan, and may have come to Earth to try to extend their lives. --Wikipedia entry: Blade Runner
It would appear the Tyrell Corporation created a little too well and replicants would escape and try to blend into the population. But because they were inherently "unstable" psychologically, they would have psychotic episodes as they approached their impending pre-programmed "death."
Having your organic androids killing people tends toward a media failure even for a corporation as large as Tyrell, so they needed someone who could clean up their messes and Deckard (rumored to be a replicant) was excellent at being at the right place at the right time for the "retirement" of said renegade replicants.
There are three Ds: Dirty, Dull and Dangerous. Jobs that are any of those three are open to automation, meaning getting humans out of the loop. Thus, robots explore Mars, build our products over and over again, control the insides of nuclear power plants and keep track and dispose of terrorists. As the population of the Earth shrinks, the value of humans increases so the push to replace them grows also. Thus replicants.
Hunting replicants is down to be dirty and dangerous. Certainly this is a job you might want to get humans out of.
Assuming that Deckard is a replicant, it is possible that the programming for him ended where the movie starts: that he was activated and pushed out of a van downtown, decided to get noodles and is picked up by Gaff. It seems unlikely, though. Bryant seems very comfortable with Deckard, which strikes to me that, replicant or no, Deckard had been a Blade Runner for quite some time.
I saw the original theatrical version on VHS back in the day and I have to say I never once got the idea that Deckard was a replicant. I have since seen both the director's cut and the final cut. I have read many excellent fan theories and arguments for both sides. The author of the book Philip K Dick said definitively that in the book Deckard is not a replicant. Harrison Ford said of the character that he is not, and something to the effect that the movie is about the juxtaposition of human vs android emotions. Ridley Scott has said that Deckard definitely is but has also stated that it is up to the viewer and is purposely ambiguous. Here is the real answer. It depends on which version you watch. If it contains the unicorn scene, Deckard is a replicant. If the scene is absent, he is not. In the original theatrical release, Gaff's unicorn is saying, "I know Rachel is with you but I'm going to let you both go because I know she won't live." The unicorn symbolizes that Rachel won't survive just as the unicorns supposedly didn't survive the biblical flood. This goes along with the chicken, which implied Deckard was afraid to take the job. And the man with the erection, which suggested Deckard was enjoying himself and getting back into the job. In the unicorn dream version, Gaff is saying, "I know about your unicorn the same way you knew about Rachel's spider."