Knights of the Borrowed Dark Trilogy by Dave Rudden

Book 1:  Knights of the Borrowed Dark

Book 2:  The Forever Court

Book 3:  The Endless King

When orphaned teenager Denizen Hardwick is unexpectedly taken from his ordinary life and brought to a mysterious fortress, he discovers that he is part of a secret world where an ancient order of knights protects humanity from terrifying creatures known as the Tenebrous. As Denizen begins to uncover the truth about his past and learns to control strange new abilities, he must find the courage to face dangers far beyond anything he has known. Across the trilogy, Denizen and his friends are drawn into an increasingly dangerous struggle between light and darkness, where loyalty, friendship and bravery are tested at every turn.

Recommended reading age:  10-14