Focusing on colors is the right angle, but it has nothing to do with Classes or Scarlet!
Anub'arak has always struck me as an enigmatic, mysterious character. He's one of the Lich King's most trusted minions, right up there with Kel'Thuzad, but unlike KT we never really find out much about Anub'arak's past. His cryptic behavior and dialogue fluctuates between loyal servant and unwilling, bitter slave. And he always seems to be a little more involved or knowledgeable about events than just some random goon. So what's the deal with this mysterious Nerubian, anyway?
Well, we know he used to be a king of the Nerubian empire, Azjol-Nerub. He fought against the Scourge when they attacked the Nerubians, and fell in battle, only to be raised into undeath by the Lich King (the Frozen Throne Lich King, not Arthas).
After destroying Lordaeron and murdering his father, Arthas returned to Northrend to seek the Frozen Throne, where he met Anub'arak for the first time.
(The video clips in this post are only 20-30 seconds long to hear the relevant quotes. Watching the full clips aren't necessary for the context of this post, but you may find them interesting. Plus, Anub'arak's voice actor is unbelievable.)
Anub'arak and Arthas meet for the first time. (0:50 - 1:22)
Also? Anub'arak's Warcraft III voice was SO MUCH BETTER than his whiny WoW voice.
Anub'arak mentions and hints a few times that he is an unwilling slave to the Lich King. When he meets Kel'Thuzad in Road to Damnation, Kel'Thuzad comments "In return for immortality, you agreed to serve him. Remarkable," to which Anub replies "'Agreed' implies choice." Furthermore, when players defeat him in the Azjol-Nerub dungeon, his dying words are "Never thought... I would be free of him...", similar last words as other unwilling Scourge champions such as Deathbringer Saurfang ("I... Am... Released.") or Sindragosa ("Free...at last...").
These occurrences would indicate that unlike Kel'Thuzad, who essentially volunteered to join up with the Lich King, Anub'arak was unwillingly forced into the Scourge's employ. However, back in Warcraft III when Anub'arak and Arthas travel through Azjol-Nerub to reach the Frozen Throne, still-living Nerubians spot Anub'arak and call him the "traitor king."
This seems oddly conflicting - if Anub'arak is a helpless puppet of the Lich King, that doesn't really make him a traitor to the Nerubian cause, does it? Perhaps the Nerubians don't realize that Anub'arak didn't actually betray them, and just assume by his presence opposing them that he is a traitor?
Or...maybe he actually DID turn on his people. Did the former king of Azjol-Nerub make some kind of secret deal with the Scourge back during the War of the Spider? When you fight Anub'arak a second time in the Crusader's Coliseum, there is no hint of rebellion or reluctance in his dialogue ("Our guests have arrived, just as the master promised," and "I have failed you, master...") - he seems a willing, loyal Scourge lackey.
Also, one particular event from Warcraft III makes me think that Anub'arak is indeed a Scourge devotee, or at least more loyal than he lets on, despite his excuses. When he and Arthas venture deep into Azjol-Nerub, they are confronted with something that shocks and alarms even the mighty Crypt Lord - Faceless ones, and later a Forgotten One.
Arthas has no idea what these creatures are, and Anub'arak immediately assumes the role of mentor and teacher. Later, he is taken aback when they come across the Forgotten One, and warns Arthas of the danger in a timbre I found curiously concerned and protective. It's almost fatherly - listen to his voice! There's real emotion there.
"They are the horrors the dwarves spoke of. I thought they were only legends. They are the faceless ones..."
"Look to your defenses, death knight! Fight as you've never fought before!" (0:30 - 1:02)
(Aside: Anub'arak is a monstrous, unstoppable undead behemoth, and the fact that there is palpable fear in his voice always sends chills down my spine.)
Now sure, I guess it could be a concerned outburst because Anub'arak feared for their very survival. But the line still seemed out of character for a reluctant servant who, let's be honest, would probably actually prefer they all die down there so he could be free of his undead curse.
And for those of you who never played Warcraft III but still think that line sounds a little familiar? It should. It's not the only time someone's said that to Arthas. Who was the other person?
King Terenas...his actual father.
"Look now to your defenses, my son, for the champions of justice gather at your gates!" (1:59 - 2:07)
I've written before how I feel parallelism and repetition are amazing storytelling devices, ones that always get make me suspicious of possible connections or hidden meanings. Hearing Anub'arak's concerned warning echoed by King Terenas years later definitely made me pause and wonder.
Will we ever find out? Unlikely, but it's not impossible. Anub'arak is dead and the Lich King's story finished...for now. We all know the Lich King isn't *truly* gone, and Anub'arak...well, he's come back once before. What's stopping from Bolvar from rezzing this oddly loyal Crypt Lord to serve the Scourge again? Maybe then we'll finally find out the truth behind the "Traitor King."