Aasimar or tiefling, I suppose. They don't really have much ties to the storyline (although with the demon stuff later on, a tiefling's a better choice than the aasimar, I suppose), but both are established races that live in Varisia, and that's a region that certainly would draw outcasts like this.
Honestly, the best race to play in Second Darkness if you want to mesh with the storyline would be elf.
Some elves are in on it. Most are not.
It's not wrong at ALL to play a race that plays a strong role in a campaign. Actually, to be specific, it IS metagamey, but in a great and productive and positive way.
Playing an elf gives you +1 more reason to want to go on the Second Darkness adventurers, in fact. Even if it's only "I want to find out the truth of the rumors."
Aren't you biased on the point of Elves? It's well known you're an elf Apologist. You even created an Iconic Elf.