OK, stay with me on this one.  I’m going off the beaten path a bit.

In the original Star Wars, there’s a scene where Darth Vader inspects the outside of the Millenium Falcon after it’s been captured.  Han, Chewbacca, Ben, and Luke, along with their robotic comedy relief, are all hiding aboard.  A quick search by stormtroopers reveals nothing, so Vader orders a thorough scan of the ship.

As he goes to leave, he stops, ponders, and says “I feel a presence, a presence I’ve not felt since…..”, which we all assume means that he senses the presence of Obi-Wan Kenobi.  This is backed up a few scenes later when Vader and Grand Moff Tarkin are having a chat, and Tarkin tries to convince Vader that Obi-Wan and the rest of the Jedi are dead.

But what if Vader wasn’t thinking that he sensed Obi-Wan, but rather Luke?

Anakin Skywalker was the father of Luke Skywalker and Leia Organa.  He was with his wife, Padme Amadala, throughout her pregnancy, and must have experienced the little intimate contacts that expectant fathers have with their unborn children.  While he delighted in the hiccups and the kicks, would a Force empath such as the universe’s strongest Jedi also have also made a connection with his unborn twins via the Force?  A baby can sense light and sound while in utero, so why couldn’t Force sensitives such as Luke and Leia also sense the presence of their father and he sense them?

This clears up how Vader was able to be sure that Luke was his son in Empire Strikes Back, even before coming face to face with him.  He realized that the presence he felt on the Death Star was his kid, put two and two together when Imperial intelligence reported back on the AAR for the Battle of Yavin, and figured out that Obi-Wan and the Emperor might have pulled a paternal fast one on him.  Vader, of course, acts on his understandable anger by convincing the emperor that he could turn Luke to the Dark Side, and proposing a father-son coup against Palpatine, which Luke turns down when he finds out that his Sith moniker will be “Darth Junior”.

In Return of the Jedi, Luke and Vader are able to sense each other across inter-planetary distances, so catching a whiff of Daddy’s little padwan while standing next to the rustbucket he’s hiding in wouldn’t be a stretch.  So, instead of sensing  Obi-Wan, a Jedi master who must have learned to camouflage his mind against such things, it makes more sense that he was able to sense and possibly recognize the presence of a son he’d thought was dead.  Of course, Vader is able to deduce that if Luke is there, then old Obi-Wan must have been hiding him and is now taking him on some damn fool crusade, which explains the discussion with Tarkin about whether Obi-Wan was there.

And with that, the geek lamp is out.  Just had that thought rumbling around in my noggin for a while and it was time to let it out.