Personality Shift?

After reading this play I was shocked to see such a change in Creon's personality. I pretty much was like is this the same guy? What happened to his leval head and reasonable thinking? He seemed to react and respond alot with his emotion especially when he felt he was being diobeyed or people were being unloyal. Like when Antogone didn't deny the accusations and when his servant person did. Another example is when his son threatned him with his own life if he did not spare his fiance's life. I thought it was totally interesting how his mindset and emotion overpowered his leval head and reasonable thinking once he took the crown. He turns to be more like Oedipus than i thought.