SOLVED. fantasy: girl with crescent moon scar learns she is a guardian [s]

[Kelli]

This book was about an odd girl who doesn't quite fit in with her mom or younger sister but learns she has a gift. Her younger sister is a princess from another world and the main character must prevent the bad guy from killing her. The main character has a crescent moon scar with two arrows going through it. I also think an owl is also involved and is sent to watch the main character develop into the guardian she is meant to be. In the end they go back totheir world and ends with a cliff hanger. Its driving me wacky and Google is no help.

[Merrilee]

This is The Watcher. There are two other books in the series: The Seeker and The Finder.

[Lobstergirl, au gratin]

Kelli, was "The Watcher" your book?

In case Kelli never returns, FYI she shelved "The Watcher" on March 2, 2014.

[Kate]

I think we can call this solved based on circumstantial evidence.