The first vampire to tell his story to a mortal. The protagonist of IV, Louis describes to a young reporter what it has been and is like to be a vampire. After nearly two centuries, he is weary of his existence. Rice originally intended his tone to sound like that of Oscar Wilde. "He was supposed to be a sort of Geoge Sanders type of character, world-weary and comical." However, Louis's voice changed when Rice transferred her perspective from that of being the reporter to seeing the experience through the eyes of Louis himself.

Louis is twenty five years old when he becomes a vampire in 1791. A plantation owner in New Orleans, he owns seven other pieces of Louisiana property. He had made himself vulnerable to the vampire Lestat while he was deep in grief over his brother's death. Louis felt responsible for this death because his brother had taken a fatal fall after Louis had refused his request to sell the plantation and use the money for religious work.

Lestat had then spotted Louis and had fallen in love with his air of despair. Although Louis had been unable to accept the possible sainthood of his brother, he sees Lestat as an angel and suddenly knows ''totally the meaning of possibility." Lestat offered him immortality and Louis took it, although at first he had begged merely to be killed.

When he is transformed, Louis is amazed at the vividness of the world around him and at the love he feels for everything. Yet he is horrified by the necessity of killing mortals for survival. Louis is a dark-haired man of the shadows who prefers contemplation and reading to action and adventure. He does not look willingly into mirrors because he sees what he cannot control. An intellectual, Louis thinks through the consequences of his behaviour rather than acting on whim, as Lestat often does. He is impelled to search for answers to the ultimate questions of life, and is especially concerned to discover whether God exists, and if so, if that makes him a child of the Devil.

Although Louis soon despises Lestat and mourns his decision to become a vampire, he finds a new purpose when he helps Lestat to make Claudia, a five year old child, into a vampire. She comes to mean everything to him, and he attempts to keep her a child, despite the evidence that inside her tiny body she has matured into a woman. He accompanies Claudia to Europe and when she is destroyed, his world changes dramatically. Louis clings to Claudia's memory and resists the approach of another vampire, Armand, who is strongly attracted to him and who manipulated Claudia's destruction in order to gain Louis's exclusive companionship. By the end of his story, Louis seems cynical; he is unable to appreciate what a gift he has in immortality.

Lestat's perspective on Louis is that he is the most human of all the immortals, the least godlike. Louis was never able to surrender to his vampire identity, and, as a result, his memories are erroneous, the "sum of his flaws." He does not kill only evildoers - as Lestat does - because he is too passive to make any such judgements. In fact, he causes more innocent blood to be shed than many of the other vampires because he simply kills almost any person he runs into.

Resentful and dependent, Louis is never quite able to rise above his human needs and is limited by his fears. He experiences claustrophobia, fear of being alone, fear of heights, and fear of his own passion and freedom. He can not move into an indefinable immortality and spends much of his vampire existence looking for security, even if it means he must see himself as a child of the Devil and thus eternally damned.

When he is later reunited with Lestat in VL, after Lestat has told his own side of the story, they are as lovers rejoined. Nevertheless, Louis never quite gets over his horror at being a vampire and when Lestat comes to him in a mortal form in BT and asks for his help in becoming a vampire again, Louis refuses. He will not willingly pass on the Dark Gift to anyone ever again.

Louis is also one of the surviving vampires in QD; Akasha spared him because Lestat loves him. He moves through the novel passively, noticed by the others but saying little, although he does brave Akasha's anger by pointing out that she has no right to intervene in the human world. She responds that he is actually the most predatory of all the immortals.

After Akasha's demise, Louis goes in search of Claudia. He follows Jesse's lead that Claudia's ghost has appeared in New Orleans and he makes his permanent home there, living in a shack behind a large but empty Victorian house. There he reads by candlelight and is seemingly unaware of all the broken windows. Lestat angrily torches this shack after Louis refuses to help him become a vampire again. Once Lestat gets his body back, however, he confronts Louis, then upon forgiving him invites Louis to live with him again in the refurbished town house. Louis accepts.

Louis is a passive character whom Rice used to express her feelings of loss and grief upon the death of her five year old daughter. At times he displays a heroic impulse, as when he decides to leave Lestat and find out for himself what it means to be a vampire, but he eventually succumbs again to his weakness - passivity - when Lestat makes Claudia. Rice eventually grew to dislike him. "At the time, I loved him. I don't now. I don't have a great deal of sympathy for a person who's that dependent and that vengeful toward people who won't fulfil his needs." Rice longed for a character with true heroic strength. Thus, Lestat replaced Louis in the remaining Chronicles as the protagonist.

However, as a character, Louis remained important to Rice. In MD, Lestat mentions that Louis has been with Armand in Paris. This is a breakthrough for Louis because he had been avoiding Paris due to the pain it had caused him from Claudia's death there. However, when Lestat goes to New Orleans after his ordeal with Memnoch, Louis is waiting for him.

David and Armand had shipped Roger's religious treasures to St. Elizabeth's. Lestat's new home, and Louis had set them up and dusted them. "It seemed the right thing to do," he said. He tells Lestat that he is inclined to believe in the authenticity of Veronica's veil, but he makes no real commitment to a religion that has long plagued him with guilt. To prepare Lestat to hear Memnoch's message, Louis helps Maharet chain him. Yet he begs Maharet not to nail Lestat into the windowless, bricked up room (probably due to the recollection of his own claustrophobic experience when Armand's coven had nailed him into a coffin).

While Lestat recovers from his shock and horror, Louis takes Wynken de Wilde's books back to the town house to read them. He appreciates the skilful artistry and invites Lestat to join him one day soon in looking through them.