Board Thread:False Info and Speculative Discussion/@comment-65.93.139.213-20150627190227/@comment-25176701-20150627192614

It's because Kate Argent aged Derek backwards (she aged him back to when he was a teenager). Kate aged Derek back to the time BEFORE he had taken an innocent life (Paige, his former girlfriend). Yellow eyes are for werewolves who did not take an innocent life, and blue eyes are for werewolves who did take an innocent life.