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I'm looking for a book I read when I was younger, around 2000 or 2001. (It was for an assigned reading group in elementary school, so it's about on a similar reading level as The Supernaturalist by Eoin Colfer, which was assigned for the same group but otherwise has nothing to do with the book I'm looking for.)
The book was about a girl and her little brother. I don't remember what happened to their parents, but the pair wound up on the run, hiding from society because they both had magical talents. In the book, the countries were holding a staged war that only people with magical talents were drafted to fight in - ostensibly because people without magic would be at a disadvantage when fighting magic-users, but actually because it was a good way to kill off everyone with magic.
The two fail to escape the war, but in the chaos of battle, they cross the border and wind up in a country they've been trained to fear. They hired at a castle or very large manor, and pretend to be citizens of the new country without magic. The girl's talent is an ability to communicate with animals so she just doesn't talk to them in front of anyone, and it's not made clear until the end of the book what her brother's talent is, but suffice it to say they can reasonably pretend not to have magic when they need to. Actually, the girl and her brother briefly join a wolf pack (before they got sent to war in the first place) and the wolves tease the girl for "burning" (cooking) her meat.
The girl, of course, falls in love with the lord of the manor, and he begins to confide in her as well, and after hearing some of his secrets, she tells him most of hers.
Major plot developments included the reveal that dragon scales in the soil were responsible for people's magic talents, and that the love-interest-guy was hiding dragon hatchlings in his basement (the governments thought they had hunted dragons to extinction). Also the brother's talent turned out to be manipulating humans to do whatever he wanted; it wasn't perfect mind control but it was enough to keep people off his scent for the most part while also making his life easier.
I think the brother ran away in the end, after causing some problems. There were lots of loose ends, left wide open for a sequel, so I really want to find this book again and hopefully read the whole series. Also if I remember right, the main character's name wasn't quite Melanie, but it was similar and had a y in the middle somewhere, but I'm less sure about that detail