Maeve is a Fae Queen, one of the three Fae Sister-Queens, and Queen of Doranelle. She is Aelin's great-great aunt through Mab's bloodline.
She has an unusually long life. On the Temple of Stone on Ilium, a port city of Terrasen and previous home to the Mycenians, Brannon admits to Aelin to not knowing whether she'd die were her heart be pierced by a blade. Additionally, he confesses her being old when he was a child.
Brannon and Maeve defeated Erawan during the first wars at the dawn of time, forcing him to fall back to another continent. A thousand years later, Elena Galathynius and Gavin Havilliard faced the Dark King alongside Brannon's weakened flame. These are the demon wars which, legend had it, Erawan had been killed by Gavin. A thousand years later it is the time of the King of Adarlan and Erawan's return, a time at which Maeve still rules with mysterious powers. Already being referred to as "old" during the first war and living through Aelin's times, Queen Maeve of the Fae is possibly above two thousand years old. It is still unknown how she has not gone through the Fading, even considering Fae's extended lifespan.
Maeve is very beautiful with elegant, regal features. She is described as the "dark sister to the fair-haired Mab". Her eyes were originally reported to be obsidian, but later they are called violet. She has moon-white skin, long fingers, and long nails.
Maeve is the kind of person who pulls strings from the shadows. She's intelligent, vicious, deceptive, manipulative and extremely dangerous. She seems to love toying with those she deems inferior to her. In Empire of Storms it is revealed that she is also very cruel, and has no qualms against very brutal punishments.
Some time before the series, Maeve sought out Fenrys and tried to convince him to swear the blood oath, but he refused. His twin brother, Connall, did swear the oath, and when Fenrys returned, he swore the oath so Maeve would leave Connall alone. She has been aware of Fenrys hatred to her, and as punishment, she does not break his bloodoath to her after doing so to other members of the cadre.
When Erawan and the King of Adarlan threatened Terrasen, Evalin Ashryver asked Maeve for help. Unfortunately, because Evalin refused to give Aelin to Maeve, the Dark Queen did not help, allowing Terrasen to fall and its people to be butchered.
Maeve's first appearance came in Heir of Fire, where she is initially introduced after Rowan first found Aelin (then still going by Celaena) on the streets of Wendlyn. Though Celaena demands answers to her many questions, Maeve tells her away, promising those answers when Rowan deems her worthy, when she has exerted complete mastery over her fire. Though it took a great deal of time for her to be able to shift between her human and Fae forms, and learn control over her gift, Aelin manages to do it. Not long after, she, along with Rowan and his "cadre" as Aelin calls it, attempt to defend Mistward against a massive Valg attack. It seems as though they were just about to lose, but after calling on her most impressive display of power yet, she forces the demons to their knees. This does exhaust her, getting her much too close to a real burnout. Rowan joins them as carranam, saving her from it.
After they've won the battle at Mistward, Aelin and Rowan head to Doranelle for the answers she claims from Maeve. Maeve does hold up her end of the deal, telling her that the Wyrdkeys can not be destroyed, rather, they must be sealed back to the Wyrdgate. Should Erawan possess all three of the keys, he'd wield insurmountable power, though he only possesses one or two.
Maeve suspects that Aelin may know where the third key is, and she begins to have the cadre whip Rowan in order to force Aelin to divulge the information. She only halts when Aelin calls on her power to encircle the city, stating that even if it is made of stone, its people weren't. She then bargains with Maeve: A ring from long-dead lover then traitor, in exchange for Rowan's freedom from his blood oath. Aelin does not realize at the time the ring's true power, and Maeve accepts the offer. Once Rowan is released, he swears a new oath to Aelin.
Though she is not seen in Queen of Shadows, Lorcan had come to the continent in search of the Wyrdkeys, to destroy the Wyrdkeys in order to protect Maeve from herself.
At some point, Maeve replaced Rowan with Cairn, a sadistic Fae warrior.
Maeve sends Gavriel and Fenrys to the continent to kill Lorcan for stealing Athril's ring from her. She amasses her armada soon after, and orders them to set fires on Eyllwe's coast, supposedly to blame Aelin for it, but also to tire out the Heir of Fire. Maeve also informs Erawan where Aelin is, to trick him into sending an army of ilken to tire Aelin even further.
Lorcan's summoning gives Maeve Aelin's location, and Aelin is separated from her friends during the Dark Queen's attack. Maeve summons Gavriel and Fenrys, then captures Elide Lochan while Aelin speaks with Elena, and when she and Manon return, Maeve confronts her. She forces Lorcan to hold Elide, and overpowers her enemy in a duel of magic. Aelin's magic was depleted from putting out the fires and destroying the ilken, so she has almost nothing left.
After Gavriel and Fenrys return to their queen, Gavriel offers to take Aelin's punishment, but Maeve refuses. Since he failed to kill Lorcan, she strips him of the blood oath for dishonor, severely weakening him. She magically disarms Aelin, and reveals that she knew about Gavriel's son, and the Lock Aelin must die to recreate. Maeve has no intention of letting that happen, because she wants the Wyrdkeys for herself. The Fae Queen also reveals that she saw Aelin and Rowan as mates in the future, and decided to leash them to her. Maeve used her powers to make Rowan fall in love with Lyria, and then she orchestrated Lyria's death. Maeve let Aelin escape Doranelle so the young Heir of Fire could lead her to the keys.
She summons Cairn, giving Aelin a choice: come willingly, or be taken anyway with Elide in tow. When Aelin agrees, she gives messages for her friends. Maeve forces Aelin to bow, then take off her shirt, which she does. The Dark Queen orders Cairn to whip Aelin, but orders Aelin to count. Cairn starts over repeatedly at Maeve's command, stopping only when one of the Fae warriors holding Aelin spots Rowan approaching. Maeve straps an iron mask to Aelin's face, and her warriors chain the assassin and put her in an iron box.
After Aelin is taken away, Maeve sends Fenrys to her ship, and speaks with Lorcan. Despite his claim that he stole the ring and betrayed Aelin all for Maeve, the queen states she has no use for a warrior she can't trust. She takes back her kill order, but also strips him of the blood oath without honor. She departs afterward, and her ship vanishes.