If you notice from the first movie the Jedi have somewhat the same rules as the Sith. There can only be one apprentice to one master. This is stated when Qui Gon wishes to train Anakin. Yoda tells him he already has an apprentice and cannot take on another. Now with the Sith, they follow the same rules (for whatever reason) and do you think that there could only be two of them because all other Sith masters were killed and there is only one true master (unlike the Jedi who have many master jedi's) so there can only be a master and apprentice (meaning Palpatine is the only master, so in theory in can only be himself and whoever is his apprentice at the time). Just a theory.
we dont know how a sith apprentice becomes the master besides the master dies, for him to kill his master is just speculations.
And Bllissbo there is a big difference, one Jedi cant have more than one apprentice but there are a lot of Jedis thus a lot of apprentices, but ONLY TWO SITHS. The siths have a rule on how many siths there can be a t a time, while the jedis sasy a jedi can only take on one apprentice. That rule by the Jedi is pure common sence though, it is hard enough to teach one person up in the Jedi way and skills
Originally posted by finti
The thing I am puzzled at though is the introduction of the only two siths thing in TPM. In Empire Strikes Back Vader`s conversation with the emperor kind of contradict this by Vader talking about turning Luke into an ally and the Emperor saying he would be a great asset.
Maybe at that time, the Emperor was planning to get rid of Vader and keep Luke as his "apprentice".
Maybe he was just using Vader (in the end) to get Luke.
I dunno, just a thought. 😉