Hi there. So, I am looking to make a Male Human paladin to RP with, you know, give it a whirl and see how it fits me. But I dread creating a Mary Sue. It doesn't make for interesting story, and it doesn't make for a fun RP environment. However, I want my character's personality to be different from the archetypical Paladin, who are more often than not Virtuous, and Honourable, and... well... Instantly likeable.
My idea is that My paladin is... well... a racist, arrogant, and fanatical prick with a intense fanatical devotion to the Light (like the scarlet crusade meets the KKK). I basically explain that he (lets call him... bob for now, until I think of a name) is the bastard (not literally) he is because his father was one of the Minor Lords of Lordaeron. Bob's dad fought in the second war (while Bob was just a pup), and much of his land and estate was ravaged by the Horde, including the loss his eldest Son and heir (who was a good and decent man), who died in battle. This left Bob's father with a bitter hatred for the Orcs, which soon extended to all non-humans (The Elves for not devoting themselves fully to the war, trolls for aiding them, and the gnomes for being shortarses... etc). This rubbed off on young bob, who grew up learning to look down on all non-humans. Eventually the plague of Undeath came and Bob was sent away to Stormwind, where he would start training to be a paladin, which he somehow completed and was initiated into the Knights of the Silver Hand (meanwhile, in an ironic twist of fate, Bob's dad was killed and risen by the plague and is currently a Forsaken... who hates himself for being a filthy undead corpse, and all of the living... for being alive/not-human. Basically he hates everyone.)
This is a guy who utterly despises the Horde and its races (spitting on their corpses, burning prisoners alive, taking orc head trophies, etc), willing to use "dishonourable" methods to win fights, revels in the act of killing Horde, and would do anything to survive to carry on his "mission" (think Jaime Lannister crossed with Ramsay Bolton... without the Incest). To him, cleansing the world of "Filth" (Demons, Undead, Orcs, Trolls, Blood Elves, Worgen.... etc) for the True sons and daughters of Azeroth (aka humanity... and to an extent the dwarves... as long as they stay in their mountains) is the highest calling a soldier of the Alliance can aspire to, with the other allies in the Alliance merely being tolerated. Basically, he thinks that the Light put him on Azeroth for the sole purpose of ensuring Human Dominance. Hes Garithos that found religion. He would fit right in with the Scarlet Crusade.
However, I understand that if a character like that were to exist, hes instantly unlikeable, and I'd like my character to evolve a bit. That is where I run into my problem. I want my character to slowly but surely shift from being an arrogant and racist bastard into a somewhat honourable and noble character. I want him to slowly discover that his purpose isnt to carry out this crusade of his, but to rather uphold the traditional values of a Paladin (Protect the weak, bring justice to the unjust, vanquish evil, etc) and slowly discover that the other races on azeroth have just as much right to live and prosper as Humanity, and that they are actually quite likeable when you get to know them. I want him to slowly discover honour and nobility. He wont be the shining paragon that Turalyon or Tirion is, but he'll be a guy willing to stand against evil and lay his life down for the innocent (regardless of race).
But, how can I do this without pulling off a "Mary Sue"? Should I tone down the douchebaggery to make the transition more believable?