No, it's not brunette, blue-eyed versions of Ruffnut and Tuffnut.
It's Sven and Katarina Hansenshiver (seriously, that's their last name) from AirHeads!, as they appear at the beginning of Book One: Ballet.
I've actually wanted to draw them in their traditional Dasani clothes (yes, their tribe is named after a brand of bottled water) for a while. Just got around to completing it today after starting it this weekend while I was waiting for Clone Wars to begin. --
And now, onto the description:
For Katarina, I decided to put her in a simple parka, along with a horned helmet. She's probably got other outfits I'll probably showcase sometime, which resemble more Dutch, Germanic, Modern Scandinavian, and Alpine styles. But for now I'm sticking to the parka because Dasani is in the South Pole of her planet. To be precise, it's supposed to be 100 miles south of hopeless and a quarter of a degree north of freezing to death. Also, that cross-body purse carries her water bottle should she get thirsty or she's being attacked by bad guys.
As for Sven, I indeed based his outfit on that of Tuffnut from HtTYD. The only thing is that his vest is made of fur rather that hide or leather like Tuffnut has in the film. He is also carrying a Viking-style shield with the emblem of his tribe (which originated with their northern sister tribe, Aquafina), and a metal boomerang. He too, like his sister, is wearing a horned helmet.