Kawthra

 MAJOR SPOILERS FOR BREE'S BURDEN 

Kawthra is described as a "dangerous and otherworldly bird." He was trapped in Maddox's Pendant, but was released. He took the form of Shadow in Bree's head, guiding her along the way. He tried to make her destroy Maddox's Pendant for his own personal gain, but Dustin made Bree realize the truth. Kawthra has also been assisting Cornelia to get what she wants.