Marcus
WHO: Marcus is one of the three elder vampire leaders of the Volturi, who rules alongside with Aro and Caius. In his early life, he fell in love with Aro’s sister, Didyme. When Aro planned to grow the Volturi to rule other vampires, Marcus and Didyme wanted no part of it so they considered leaving. Aro then found out their intention to defect from the Volturi, and he killed Didyme and forced Marcus to stay. He knew he couldn’t make Marcus stay without a fight so he had Volturi member, Chelsea, use her powers to break the bond that Marcus and Didyme had.
NIGHT OF THE LIVING DEAD: Losing Didyme caused Marcus to become emotionless, unfeeling and literally zombie-like. Could this be a result of Chelsea’s power or was Marcus in so much pain that he didn’t care about anything anymore? We saw further proof of his “no care attitude” when he voted against destroying Renesmee in Breaking Dawn, all the while looking bored as if he just wanted the battle over with.
USEFUL ABILITIES?: At first glance, would you think Marcus’s special ability of recognizing strengths in relationships is of any use to Aro? If you are in the position of power and leading an organized vampire coven, it is probably one of the most valuable traits to have.
For example in a battlefield, Marcus can see the relationships of those in command and those taking orders. Seeing the bond between comrades in battle could potentially give them a fighting advantage by knowing who to take out first. He would also be able to see if loyalty and devotion is fading and if defection is in the works, which would come in really handy in a position of power.