So, another Star Wars themed post talking about the Sith and the Rule of Two. In The Empire Strikes Back and Return of the Jedi, both Emperor Palpatine and Darth Vader are in agreement to turn Luke Skywalker to the Dark Side. Now whether this means to make him a Dark Jedi, like an Inquisitor or a full fledged Sith Lord is never revealed. If they were able to turn Luke and make him a Sith Lord, this would mean that Vader and Palpatine would be abandoning the Rule of Two, which states that there cannot be more than two Sith Lords at a time, a master and an apprentice.
Given that the Emperor thought that the Rebellion was about to be crushed and the Sith would have full control of the galaxy, Palpatine may have decided to abandon the Rule of Two and have more force sensitive people trained in the ways of the Sith. Since the Sith would no longer have to operate in secrecy, they can operate as they did before their defeat by the Jedi and the rule of Darth Bane.
Conversely, Palpatine and Vader may have decided for themselves that the Rule of Two should be kept and each wanted to turn Luke to their side. Palpatine wanted Luke to join the Dark Side so he can train Luke as his new apprentice. In their time as master and apprentice, Palpatine has been watching Vader and identifying his weaknesses. Feeling that the life support system and artificial limbs are hindering Vader from being as powerful as he could be, Palpatine may have decided to replace Vader with Luke.
Vader also may be planning on using Luke to overthrow the Emperor. Vader has seen Palpatine grow older and frailer. He feels he can learn no more from his master and plans to use Luke’s power and abilities to overthrow the Emperor. In this case, I feel Vader would be the one to win over Luke, because they are father and son and Luke’s been wanting to get to know his father for his entire life.
Anyway, those are just some thoughts regarding Star Wars. Because a bunch of jerks have decided to make Star Wars a divisive topic, I am not allowing comments on this post. Sorry if this inconveniences anyone.