Alrighty.... Just a few things:

-- Firstly, please glance through the other CSes and try to make his personality section emulate those. 4-7 words. I'm looking for a list of adjectives. 

-- Considering the exact origin of Dark Nuts aren't really spelled out, I'm totally fine with your decision to make them be a race from some far away place. "Between the Gerudo Desert and ocean beyond" denotes that it's a part of Hyrule and that's not really something I want, however. I'm fine with the creation of small villages and towns, but the creation of a large city (which is what Ontheon sounds like) is a bit of a bigger deal. Especially when it's a city filled with dark creatures created and/or used by Ganondorf when he tried to take over Hyrule. Personally, I'm more in favor of them being creations of Ganon, but since it's neither integral to the plot nor crystal clear canon, I'm willing to bend. 

"It should also be mentioned that shooting Light Arrows at a Darknut, even in full armor, will instantly kill the unfortunate Darknut, suggesting that Darknuts are followers, or perhaps even creations of, Ganondorf, seeing as regular, fire, and ice arrows will simply bounce off a Darknut's armor." (Zelda Wiki.)

It may also be worth mentioning that the Dark Nut tribe could have originally been created by Ganondorf but abandoned following his defeat. 

-- Then there's this part:

"He was getting old and he did not want to die in some fighting pit. So he decided to see what else Hyrule had to offer for him, and one day set off."

I... can't fathom why a Captain that holds honor above all else would just get bored and run away like that. Especially into a land that would surely hate his guts-- the Darknuts would NOT have a good reputation amidst other Hyruleans. So what would he think Hyrule could possibly offer him, I wonder? It would make far more sense for his kind to be banned from Hyrule as opposed to the Zuna-- who I highly doubt the King would have any reason for banning. Most likely he and most of Hyrule have no idea what/who Zuna are since (If the Desert of Doubt is to be seen as the equivalent of the Haunted Wasteland, which I think makes the most sense) races other than the Gerudo aren't typically permitted to go there. And most folks wouldn't be so keen to visit such a place anyway, I'd bet. 

But anyways, why wouldn't him hearing a mysterious voice in the night be enough? By the time the RP has started he's been hearing the voice for a month straight. I think I also ought to mention that I really want everyone starting off in Kakariko. I'd rather not have to fabricate a whole other plot arc that's on the other side of Hyrule and only applicable to one person....

--I would probably relabel his skill as a survivalist to better reflect that fact that he has experience with only desert environments. If his tribe originated from the desert, I doubt they'd know much about Forests and mountains and other such regions. He's also going to need a slot dedicated to strength. Otherwise hefting around all that crazy thick armor would be nigh impossible.