To ask a related question… if Sidious is all the Sith, I take that to mean that from perhaps Darth Bane onward the Master basically possesses the apprentice, and on and on it goes.
So, Darth Sidious ought to somehow contain all his predecessors, perhaps even really being Darth Bane. If this is so, how is one to read the line in ROTS in which Palpatine appears to revel in killing his master? “He could save others from death… but not himself.”
Sidious would essentially be Plagueis, right? It would make more sense if the line were something like “he thought he could kill him but he couldn’t.”