For the Sith Order under the Rule of Two (i.e. from Darth Bane to Palpatine), does the Sith Apprentice hold the title "Dark Lord of the Sith"? Or is the title reserved for only the Sith Master?
In the (Legends) Bane trilogy, it appears to be reserved for the Sith Master. For example, from Dynasty of Evil:
That was why Bane had chosen Zannah as his apprentice: she had the potential to one day surpass even his own abilities. On that day she would usurp him as the Dark Lord of the Sith and choose an apprentice of her own.
Later, Darth Zannah affirms that the Apprentice becomes the Dark Lord upon killing the Master:
The Master will train his apprentice in the ways of the Sith, until one day she must challenge him. If she proves unworthy, the Master will destroy her and choose a new apprentice. If she proves the stronger, the Master will fall and she will become the new Dark Lord of the Sith, and choose an apprentice of her own.
However, Darth Vader -- who never became the Sith Master -- appears to hold the title. He is referred to as the "Dark Lord" in the movie scripts, as well as in the canon novel Tarkin (albeit always from the perspective of Moff Tarkin, who is not a Sith). Probably on this basis, Wookieepedia's canon article on the title says that the title was "shared" by the Sith Lords under the Rule of Two.
There appears to be a contradiction, in that the Bane trilogy reserves the title for the Master but the canon sources do not. How is this explained? Did the Sith Order start giving the title to the Apprentice sometime after Darth Bane and, if so, when? Is the Bane trilogy simply wrong to reserve the title for the Master (it's Legends, so canon supersedes it)? Or did Darth Vader not really hold the title?
The last option (that Vader didn't really hold the title, but was publicly assumed to hold it) seems possible for several reasons:
- Vader is never called the Dark Lord by Palpatine, and never calls himself the Dark Lord. He is only referred to as the Dark Lord from an out-of-universe perspective (e.g. in the scripts) or by non-Sith characters (e.g. Tarkin) who wouldn't know his true title(s). Within the Sith Order, it's possible Vader doesn't really hold the title.
- Palpatine was not known to be a Sith by the general public, so from the public point of view Vader was the only Sith and therefore the Dark Lord.
- Out-of-universe, there may be a bit of a retcon here: Lucas didn't initially intend Palpatine to be a Sith and started calling Vader the Dark Lord in the Episode V script; when the Emperor's character was changed to be a Sith, he was stuck with Vader's title.