Contagonist is the term in the complicated [understatement] Dramatica matrix of character and plotting. ?It’s an obtuse, arcane term for the role of the deflector character. ?A deflector character is one who would turn the protagonist/main character/Hero (take your pick) away from heeding “the Call”, pursuing his objective goal. ?In contrast to the antagonist who directly blocks the protagonist with malicious intent.

The deflector character is not trying to defeat the protagonist. ?He usually believes he’s saving the protagonist from trouble, from the consequences of a foolish decision — “it’s for your own good”. ?(Or “for your own good” is the deflector character’s overt reason for?covert intentions,?manipulating the protagonist for his own self-interest.)

In “The New Hope” the deflector character is clearly Luke’s uncle who wants to keep Luke down on the farm and whom Luke uses as his excuse for initially rejecting the Call from Obi-Wan. (Hence, Obi-Wan’s reply: “That’s your uncle talking.”)

In “The Return of the Jedi” I think it’s more complicated. ?Vader’s role as a deflector character is conditional and with overt rather than covert intent: ?”If he could be turned, he would become a powerful ally” he tells the Emperor.

The Emperor: “Can it be done?” ?(The dramatic question that frames the rest of the episode.)
Vader: “He will join us or die, Master.”

So, if Vader can’t deflect Luke, then he will kill him. ?He will act as an antagonist. (And spiritually, Vader is always Luke’s antagonist in terms of his attempt to kill ?Luke’s “better self”, ?get him to embrace the dark side.)

And if one wishes to engage in a scholastic debate over who is the one and only, true, unambiguous, certified, must-be antagonist — Vader or the Emperor — knock yourselves out.

Any way you slice and dice the roles, the Obligatory Scene, the High Noon scene is — and must be — a showdown between Darth Vader and Luke Skywalker. ?And when it happens the Emperor is nowhere in sight.

Why? ?Because the thematic core of the story entails two characters struggling for Luke’s soul — his father and his mentor. ?The Emperor has a big stake in the outcome, but he’s not a hands-on central participant in that struggle. (Vader, as Luke’s father, has more at stake than the fate of the Empire, ?an immeasurably deeper emotional investment in Luke than the Emperor will ever have.)

As Nir Shelter well observed in another thread, definitions are fuzzy and roles can overlap. ?I understand and empathize, but after years of trying to arrive at precision and clarity, I finally realized I was chasing ?a mirage.

My 2.5 cents worth.