Oath on Obsidian

Five Imitarian brothers find themselves in a precarious position when, on their twelfth birthday, they shift into an Ordin born - one each night - before shifting and the next taking their place. They set out to discover the reasons, but they must take precautions. The Ordin born, who possess no magic, do have the ability to take an Imitari's magic through the Caerimonia.
They must negotiate how to maintain a public appearance while concealing their true identity; but, how long can they accomplish this?

There are The Imitari and The Ordin born. Ordin born have alikeness to humans while the Imitarian stand less than a hand tall.