M.J. Sewall 
The Trials of Boy Kings [EPUB ebook] 

The young kings stand oceans apart.
Old truths have been discovered, putting them both in grave danger. Held captive by their fate, the two sworn enemies that chose their king will come crashing together, but in ways neither side could see coming.
A new threat rises as the distant leader known as the Father steps out of the shadows, threatening his enemies with a deadly new weapon.
Facing destiny-altering choices, both kings must hold on to the allies that will bring down their true enemies. But can they set right the history that has been stolen?