Tyler talks with Reign about holding on to his humanity and keeping up the fight to keep this beast within him in hibernation still. But later he does unleash the beast.
At the Masquerade Ball, Tyler parties with Matt and Sarah, when Matt starts attacking Tyler (Because of Katherine's compulsion). Caroline rushes in and breaks up the fight, but Matt struggles to get out of Caroline's clutches and says that he needs to finish it. Caroline punches him unconscious. Tyler is shocked about what just happened. From behind Sarah grabs a letter-opener from the desk and says "Matt failed. If Matt fails, I can't" and stabs Tyler in the shoulder, and Tyler pushes her away with great force and she hits her head on the edge of the desk and lands on the floor. Tyler runs to her and shakes her and yells that she needs to open her eyes and that "this can't be happening!". He runs to the other side of the room in panic. Caroline checks her pulse and by the look on her face, Sarah is dead. Tyler start screaming and turn into a werewolf. Caroline wonders about what is happening but Tyler yells that she needs to get away. He then shows his face, and his eyes turns yellow. Tyler starts to suspect something is different about Caroline, being the first to notice that the injuries he sustained from Sarah already healed before he noticed it himself. The first time he confronts her, she takes him down easily and at first he thinks she's a werewolf too. However, on the second confrontation, Caroline reveals to him that she is a vampire. Tyler is shocked at first and asks her if there were more, but she denied, keeping Damon and Stefan's true identities secret. After learning each others secret, Caroling decided to stay with Tyler through his transformation.