The Fallen Moon Series by K.J. Taylor

Being chosen as a griffin's companion has allowed Arren Cardockson to gain a place of status within the land of Cymria. But Arren can never escape the prejudice that comes with his Northerner slave origins. For chained within the Arena where rogue griffins battle to entertain the crowds, there lies another soul crying out to be freed-a kindred spirit that will allow Arren to fulfill his destiny and release the darkness in his heart.

Although he was once chosen as a griffin's companion, Arren Cardockson was reviled, betrayed, and ultimately killed. Brought back to life by a power beyond his understanding, Arren flees for the frozen sanctuary of the North. With the man-eating griffin Skandar by his side, and an entire country hunting him, Arren has little hope of reaching the place of his ancestry and of lifting his curse. But then he comes across a wild woman who may hold the key to making his lifeless heart beat once more.

After promising his allegiance to the Night God, Arenadd Taranisaii escapes death for the second time and vows to free his people. With the dark griffin Skandar by his side, Arenadd begins to gather an army and prepare for war using the power gifted to him by the Night God to move through the shadows. But even as Arenadd's strength grows his nemesis sets out for the Island of the Sun, seeking the one weapon that can truly kill Arenadd, the man without a heart.