… apparently The Keeper and the Rune Stone by Paige Pendleton will be right up your alley, and today the Kindle version is free at Amazon.
[Related: Did you know that you can convert your Nook into an Android tablet? I didn't, but my kids' dad recently converted their Nooks, and that allowed them to download Kindle apps and then I registered my son's Nook to my Amazon account. Now when I see freebies like this, I can grab 'em and send them directly to him! I love it.]