Lestat first hears of Marius when Armand explains how he became a vampire. When Armand first knew him in the fifteenth century, Marius had been a Venetian nobleman and artist. He chose to work among mortals, have mortal apprentices, and make religious art. It was Marius who bought Armand from a brothel and fell in love with him. He then painted The Temptation of Amedeo in an attempt to capture on canvas Armand's qualities forever, and he made Armand so that he could join with another kindred soul. Marius desired their bond to be permanent, but their happiness became short-lived when, only six months later, Santino's coven put a torch to Marius and captured Armand. Marius managed to escape to his secret shrine in the mountains of northern Italy, where he healed himself by drinking the healing blood of Those Who Must Be Kept. He did not see Armand again until 1985 in Sonoma, although he had been aware that Armand was suffering through three centuries of loneliness.
Marius is over 2000 years old.
Marius was created by a dying vampire who turned Marius agains his will. This gave Marius immense power and over the years his immortal powers have grown to a god like level. He can levitate, he is telepathic and he can ignite other immortals with only his mind.
After hearing about Marius from Armand, Lestat decides Marius could teach him a lot about the best way of living as an immortal. He sets out to find him, for ten years leaving messages all across Europe until Marius - won over by Lestat's persistence and innocence - finally comes to him. Marius then takes Lestat to his sanctuary on a Greek Island. With blue eyes and white-blonde hair, Marius wears red velvet, no matter what the era. His face astonishes Lestat: "What one of us could have such a face? What did we know of patience, of seeming goodness, of compassion?
Marius seems to depict a pure image of human love. Gentle, vital, and noble, he emanates a godlike power, although he is more human than any vampire Lestat has ever encountered. Marius does have the ability to perform supernatural feats like levitation and mental telepathy, but he prefers to do things the human way. To him, human gestures are more elegant and require less energy. "There is wisdom in the flesh," he claims. His goal is not to transcend human emotions but, rather, to refine and understand them. He also seems connected to everything around him - thus being the antithesis of Armand, who is connected to nothing. Marius shows Lestat Those Who Must Be Kept - Akasha and Enkil, the original vampires - then tells his own story.
The bastard child of a Keltic woman and a wealthy Roman, he was a citizen of the Roman Gallic city of Massilia durning the time of the Roman Empire. Never bored or defeated by life, he always felt a sense of invincibility and wonder. An important life theme for him was the idea of the existence of a continual awareness because Marius desired that nothing spiritual ever be lost. A scholar, he was, at the age of forty, at work on a history of the world when a Druid abducted him. Because he was an extraordinary human being, the Druids wanted him to become their new god and thus replace the God of the Grove, a burned and crippled vampire who no longer inspired their ceremonies. The Druid priest, Mael, forced Marius to learn the Druid language and customs.
On the night of their great Feast of Samhain, the Druids took Marius to the giant oak tree where they had imprisoned their other god. Inside it, the vampire god taught him the lessons of the vampires and urged him to go to Egypt, to find out why vampires in other places - and himself as well - had been burned or destroyed. After being made a vampire, Marius broke free of the Druids and pursued this new course. In Alexandria, Marius encountered other burned vampires. One of them took him to the Elder - a vampire who told Marius about Akasha and Enkil, the vampire progenitors. Marius learned that he, like other vampires, is vitally connected to them, and that if they suffered harm, he and all other vampires would experience similar damage. Since they had been placed in the sun, as a consequence vampires everywhere had been burned or destroyed.
The recognition that whatever happens to them happens to him upsets him, although it affirmed Marius's desire for the existence of a continual awareness. That same night, Akasha asked Marius to take her and Enkil out of Egypt before the Elder - the one who had deliberately placed them in the sun - destroyed them. Marius took them as requested, travelling with them around Europe until he settled on an island fortress in the Argean, where he built a shrine for them and where he now sits with Lestat. Marius feels he is truly immortal, that he is the perfect guardian for Akasha and Enkil, and that his is now the "continual awareness." He is in love with humanity's progress, although he realises that human evolution away from belief in gods and superstitions has made him, as a vampire, obsolete.
No purpose is left for him. After Marius tells his story, he sends Lestat away to live on his own, for the equivalent of one mortal lifetime. He tells Lestat not to look to history to give himself meaning because the dilemma of how to live one's life is always a personal one. However, Marius vows that he will be available if Lestat ever needs his help, and extracts from Lestat the promise never to tell anyone about him or his whereabouts. They do not meet again until the twentieth century, when Lestat becomes a rock star and reveals the whole vampire history in his songs. By that time, Marius has moved his immortal charges to a northern wasteland where he plays Lestat's music videos for them.
In response, Akasha rises and destroys the shrine, trapping Marius in ice for ten days. Marius sends out a signal of danger to the other vampires. His child and lover, Pandora, urges Santino to help dig Marius out, and while Marius survives, the experience has humiliated and spiritually bruised him. Marius joins those vampires who stand against Akasha and Lestat and their rampage of destruction, and uses his own belief in the need for human evolution to attempt to reason with Akasha. After her demise, he urges Lestat not to write about it, but Lestat ignores his advice. The surviving coven drifts apart, and Lestat believes that Marius has gone to Asia. He appears in BT only as an angry presence at Lestat's antics; he turns his back on Lestat in front of Louis's burning shack as if he is finally finished with him.