The Leaders
Aro, Caius and Marcus are the leaders of the Volturi. They command the Volturi's guard and act as representatives when dealing with other covens. Aro has the ability to read every thought a human or vampire ever had simply by making physical contact with them. Marcus has the ability to sense relationships, as demonstrated in New Moon. Unlike Aro and Marcus, Caius is not gifted.
Aro, Caius and Marcus are the leaders of the Volturi. They command the Volturi's guard and act as representatives when dealing with other covens. Aro has the ability to read every thought a human or vampire ever had simply by making physical contact with them. Marcus has the ability to sense relationships, as demonstrated in New Moon. Unlike Aro and Marcus, Caius is not gifted.
Aro
The early life
Approximately a decade after having been transformed into a vampire, Aro also changed his sister Didyme, with hope that she would posses an ability akin to his. However, she was blessed with an ability not as useful to him; the power to make people happy. Aro's colleague Marcus fell in love with her, and she with him. However, Marcus and Didyme eventually became discontent being involved with Aro's rising organization, the Volturi. In order to prevent their leaving, Aro killed Didyme: Marcus was too integral to his plans to lose. Aro then had Chelsea use her ability to ensure Marcus remained loyal to the Volturi.
By 500 AD, the Volturi had usurped control of the vampiric world from the Romanian Coven. Aro ruled the Volturi, along with Marcus and Caius, although he generally acted as its' spokesperson. The Volturi, under the three ancients' leadership, set down the laws of the vampire world and severely punished those who did not adhere to them.
Carlisle Cullen came to live with the Volturi for some time, and became close friends with Aro. However, Aro was alarmed at Carlisle's preference to "vegetarianism", and believed that this would only weaken him over time. Carlisle eventually left to find other vampires like himself.
Powers and abilities
As the apparent leader of the Volturi, Aro is exceptionally talented. Being vampiric, Aro is blessed with superhuman strength and speed, and has vastly enhanced senses. Aro also possesses the supernatural ability to read minds; his ability is far more powerful than even Edward Cullen's, as he is capable of hearing every thought a person has ever had. However, his powers are limited since he requires physical contact to use this ability, and cannot read minds from a distance.
Caius
Early Life
Caius was born about 1000 BC, and at some point became a vampire. He later joined the Volturi, along with Aro and Marcus. It is unknown if Caius ever met or knew Didyme, Marcus's wife and Aro's genetic sister, or if he knows that Aro killed her himself. Later two female vampires joined the Volturi: Sulpicia and Athenodora, who both were cousins. Athenodora later became Caius's wife. Some 2000 years before Breaking Dawn, he was nearly killed by a werewolf in a fight, and never got over it, so he hunted werewolves to near extintion. He also participated in the extermination of the Immortal Children, which he deemed to be dangerous.
Marcus
Marcus is one of three vampires in Italy who live what Edward described as a very civilized and educated lifestyle. Carlisle found them while on his own search for the truth behind his nature. The Italian vampires tried to cure Carlisle of “his aversion to his natural food source,” but they failed. Their likeness was depicted in several painting by Solimena.
Relationship
Marcus lost his mate, Didyme when her brother Aro killed her. He never knew Aro killed her. That loss, over the centuries, turned him into the apathetic zombie he is today
Power
Marcus has the ablility to recognize relationships
