Sith and their Apprentices and Palpatine

[Stravo]

I've complained in the past about the incongruity of Palpatine wanting to ditch the known and still powerful quantity of Darth Vader for the fantastically powerful Luke who most certainly would have pwned Palpy in a very short amount of training time. Rationally it made no sense to me. Vader was a controllable and less powerful tool that could never take him straight on.

Its almost as if Palpy is searching for a worthy successor. Someone that can take him down would be worthy of being a Sith Lord.

So is that part of the Sith psychology? They know they tend to turn on each other (rule of two) so a Master must assume that his apprentice will eventually try to take him down. Does the master search for someone that if they do get killed is worthy of taking on the Sith mantle?

OR can this obsession be limited to Palpy for another reason?

For example, Darth Plagueus mastered life creation and taught (or supposedly) taught Palpy everything he knew. Palpy decides to kill Plagueus in his sleep (not direct confrontation so perhaps Palpy broke an unwritten rule that if you're going to off the master it should be at the point of a lightsaber or force lighting) and realizes afterwards he doesn't know everything. In this instance Palpy was not a worthy successor to DP. He didn't carry all his master's secrets and perhaps that last ability is the Holy Grail of Darkside powers.

This drives Palpy to have to find a powerful enough apprentice to unlock that final secret. Vader wasn't it, so then it must be Luke. Luke represents that last chance at unlocking the final secret. So it actually becomes rational that he is willing to take the chance at dumping Vader for a fantastically more powerful apprentice.

[Darth Wong]

The Sith "master and apprentice" system would never have survived for millenia if there was not some means of succession that people were willing to accept and live with. Otherwise sooner or later some Sith Lord would have changed the rules, refused to take on an apprentice, or deliberately left him badly trained so he couldn't defeat him and the Sith would get weaker over time.

Notice Palpatine's line to Yoda where he says that Vader will someday be more powerful than either himself or Yoda. I feel that the Sith actually believe that the Dark Side is a cause worth fighting and dying for, and that when they are weaker than their successors, it is just and righteous that the apprenctice should kill the master and take his place.

It's not as if weirder or more nihilistic ideologies cannot be found in real-life history.

[Darth Garden Gnome]

If we are to venture into the EU a bit here, we find that by ROTJ Palpatine already has the ability to effectively live forever with his spirit transfer technique from Dark Empire.

However, it may not be what the technique actually entails (eternal life), but simply the fact that he does not know it, that drives him to find another apprentice.

Alternatively, Palpatine may have just wanted to have Luke for the sake of having a more powerful underling to do his bidding, and figured he would bend over backwards and take it like a good little farm boy, forseeing the event (as he said he had) to unfold without incident.

[Illuminatus Primus]

Palpatine was deeply more powerful than Luke in ROTJ, and there's no guarentee with Palpatine doing the training he'd ever reach just powerful enough, and even so, when he kills Palpatine and has zero political base, what will he do? And then Palpatine reincarnates and kills him.

But in ROTS its a different ball-game. Palpatine is searching for the ultimate Sith superman, and not betting on his own eternal life.