7. Deckard Is Gaff's Replicant Replacement - Blade Runner
"Is Deckard a replicant?" It's a question that everyone still feels they have to ask after seeing Blade Runner, despite Ridley Scott coming out and explicitly stating that Harrison Ford's detective is indeed a manufactured human. He's even re-edited the film twice to remove confusion; the answer "yes" is now less a fan theory and more the conventional reading of the film. This next part, however, is not.
You see, not only is Deckard a replicant, but he's one created specifically as a replacement for another Blade Runner, Gaff, fake memories and all. Edward James Olmos' character spends most of his time in the film making little foil origami models of great significance, but only because, walking with a stick, he's clearly out of commission. And in lieu of that, instead of training up a successor for a job with low-levels of activity, the LAPD instead got one made with Gaff's memories implanted.
On a base level it provides an explanation for one of the central Deckard-is-a-replicant clues - Gaff knew about the unicorn dream (evidenced by the final origami model) because it was one of his own dreams - but nothing else from the film works against it. Throughout the movie, Gaff shows a quiet animosity towards Deckard, which given this theory is more than justified - is there any bigger insult to the hunter of replicants than being replaced by one? OK, maybe he's just an !*$%, but this idea better justifies his third act change of heart; when he pops up after Roy Batty's death to tell Rick he's "done a man's job" he's really showing acceptance of Deckard's humanity.