Marcus is one of the leaders the Volturi coven. He possesses the gift of relationship identification, allowing him to see the emotional ties between individuals.
When Marcus became a vampire, he acquired the power to read the emotional ties between people. Aro first met him shortly after his own transformation. Together with Caius and Athenodora, he formed the core of the Volturi. Marcus then met Didyme, who was Aro's biological sister, and became her mate. Didyme was blessed with the ability to make people happy.
Marcus and Didyme were very happy together until she was killed in battle by werewolf. After he avenged her death, Marcus was ready to end his life but Aro couldn't deal with losing another family member so had Chelsea use her ability to bind Marcus to the Volturi. Marcus was greatly resentful of Aro doing this but Aro believed he could find happiness again.
By 500 AD, the Volturi had usurped control of the vampire world from the Romanian coven. Marcus ruled the Volturi, along with Aro and Caius. Now as the ruling body, they created laws for the vampire world and punished those who did not follow them.
Marcus, as well as the rest of the Volturi, are both feared and respected throughout the vampire world as the guardians who keep the human world ignorant of the supernatural. He is also known to be respected in the human world as "Saint Marcus", the holy priest who drove all the vampires from Volterra. His national holiday, St. Marcus Day on the 19th of March, is celebrated each year by the people of Volterra. The legend most likely developed out the fact that the Volturi do not permit hunting within the walls of Volterra.
In March 2006, Edward Cullen comes to Volturi seeking to be destroyed after being lead to believe his love, Bella Swan, killed herself. Aro is interested in Edward’s ability to read minds from a distance, and offers him chance to be apart of the Volturi Guard, which he declines. The leaders refuse his demand.
When Edward's act of trying to force the Volturi's hand fail, he along with Alice and Bella are taken to see the leaders. As Marcus look into the emotional ties between Bella and Edward, he sees it isn't love but deep obsess that binds these two together and is disgusted by this.
After Alice reassures them that Bella will be turned soon, they are allowed to leave.
- Twilight (Mentioned only)
- New Moon
- Eclipse (Mentioned only)
- Breaking Dawn