Yeah but I think I know what Ad_Hoc is getting at. If you decided to call your self a Paladin of your tribe, why use the word Paladin? The tropes associated with that image is not likely what you're going to play, at least in practice.
That being said, as a DM, if a player gives good enough reason (or even a half way decent reason) I'll allow a lot of things. An honorbound barbarian whose rages they decided to call a tranquil fury, righteousness streaming from his every muscle? Paladin like, sure. I don't know, however, if the reverse could be true. Could there be a savage barbarian from an outlander tribe who follows the Oath of the Ancients? Maybe, if the refluff was something around "Beauty is emotion, and in my states of deep meditative rage I can see the beauty in every strike."
In both cases NPCs would see the character as not just another adventurer (as far as that trope would get you, anyway; most adventurers are special in my games) but someone even weirder than normal. Assuming they knew what it meant to be a paladin or a barbarian, anyway.
I think some classes are definitely easier to refluff than others.
Then again, Lombra did say there were no mechanical roleplay rules in place to force a certain persona. That is 100 percent true.