When Did Vader Find Out Luke Was His Son?

Those of us who watched the original Star Wars trilogy in theaters, years apart, were well aware of George Lucas' habit of making the story up as he went along. It was clear as soon as The Empire Strikes Back came out. The prequels muddied the waters even further. Vader interacted with Luke while apparently having no knowledge of his name or background, then later knew all about him, yet either had no feelings about the twenty years or so in between or else hid them from the Emperor well. Here, we get a summation of what we know from a YouTuber named Viral Killer. I tried to keep up with all the facts, but I was so blown away by his wonderful accent that I had to listen twice. Viral Killer has lots of videos looking deeper into the character of Darth Vader and other Star Wars characters.