vote_for_palpatine said:

ESB: Vader wants Luke Skywalker desparately. He is using a ton of Imperial resources to track down this one guy. (Of course, we do not yet know about their blood ties) True, finding Skywalker means finding the Rebels, but the course of the movie makes clear that finding the Rebel base is the second bird - Vader's one stone is aimed at Luke. (If that weren't the case, why did'nt Vader's ship try to follow the Rebel fleet out of Hoth instead of the Millennium Falcon?)

he didnt know luke was his son ye- oh wait it says so in the crawl