Remathilis
Legend
See, while I agree that he'd probably have the Acolyte background, I have no interest in him having learned those skills from some barbarian tribe. I much prefer the idea that it's either unique to him, or to a particular order of warrior monks. Mechanically/out-of-character, it may resemble barbarian rage, but in-character/flavor-wise, they're not related whatsoever.
But then, assuming it fit the flavor of a campaign (and how dragons were portrayed in that campaign), I have no problem whatosever with reflavoring an infernal-pact warlock to a dragon-pact warlock, either.
Yeah, there's my hangup: it sounds a bit like "I want to be a barbarian, but I don't want the baggage of being a tribal/backwater character, so I'll say he's a priest/monk and avoid those connotations." I know that's not what you're going for, but I've seen a few too many players try to do that. And it a lot of cases, its to get the best mechanical benefit without regard to the class archetype attached to it. (My 3e example of the guy who took 1 level of barbarian with his "thief" because he wanted +10 ft of movement and extra hp when in melee)
Class names mean something. If they didn't, they'd all be generic descriptors (fighting-man, healer, magic-user, skill-expert, outdoorsman, unarmed warrior, etc). Instead, most provide some archetype. You don't have to hew close to it, but it has to be there somewhere.
YMMV, IMHO, and all that jazz.