The Leanansidhe has Reddish hair that curls down past her hips. She has flawless skin, high cheekbones, and lush, full, bloodred lips. Her eyes are golden and have vertical slits instead of pupils, like a cat.
She is considered one of the higher Sidhe within the Winter Court and held a position of power up until her imprisonment by Mab. She has made no objection to Harry Dresden calling her "Lea", although she has objected to being called a faerie rather than one of the Sidhe.
Despite being 'treated', it is still readily apparent that, by mortal standards, she is less than mentally sound, evidenced by her childlike behavior and excitement at times of extreme violence such as Dresden's victory in the duel near the conclusion of Changes.
The Leanansidhe made a deal with Harry Dresden when he fled from his adopted father, who had tried to coerce him into performing black magic at the age of 16. The Leanansidhe agreed to give Dresden the strength necessary to defeat DuMorne, in exchange for his life, fortune, and power. In actuality Dresden already had the strength he needed, so all Lea really gave him was confidence, probably saving his life and mind. Her torture sessions essentially handed Dresden Dumbo’s magic feather: they made him think he was better, stronger, and faster without actually altering a damned thing, otherwise. And it worked. He overcame DuMorne. This deal was reinforced by another similar deal made by Dresden during the course of Grave Peril. The debt from these deals was sold to Queen Mab before the events of Summer Knight.
In the seriesEdit
- Main article: Grave Peril
In Grave Peril, the Leanansidhe has spent many years attempting to get Harry Dresden to honor his bargain and become hers to which she has expressed the desire to turn him into a hellhound as evident in which Lea chases Dresden and Michael Carpenter in the Nevernever.
During The Nightmare's attack on Dresden and Charity Carpenter, Lea assists Dresden by providing him the advice needed to thwart the Nightmare's attack. In exchange, he promises again to follow her, which he soon breaks, resulting in her gaining possession of Amoracchius. It also allowed Lea more power over him, allowing her to heal a cut on his head.
Lea appears again at Bianca St. Claire's masquerade party where it is revealed that Dresden is weakened in her presence due to breaking his word to her three times. Susan bargains with Lea to cure him and in exchange Lea takes a year of Susan's memory. The faerie seals the bargain and leaves Susan with no memory at all of Dresden - the year taken was not contiguous, but rather consisted of every moment Susan had spent in Harry's presence. At the same party, Lea is gifted a small black case and in return she gives Amoracchius to Bianca. 
The next time Lea catches Dresden is again in the Nevernever. After he poisons himself, Lea makes a deal to do him no harm for a year and a day provided he remains in the mortal world. She points out that no such deal was made with others in Faerie and summons allies to chase Dresden down.
- Main article: Summer Knight (novel)
In Summer Knight, the Leanansidhe has sold her debt over Harry Dresden to Queen Mab. She does, however, indirectly assist Dresden, by posing as an elderly woman calling the cops during a fight with Grum.
When Dresden summons her, she informs him that her gift from Bianca St. Claire was a dark-handled Athame of great power. She then takes him to an ethereal Chicago-over-Chicago and a great Stone Table on his task for Mab.
- Main article: Dead Beat
- Main article: Proven Guilty
In Proven Guilty, the Leanansidhe is shown to be trapped in Arctis Tor, exhibiting signs of a personality more ruthless and devious than her dominant one. She reveals the nature of Lloyd Slate's torture and that Mab imprisoned her as a result of her own arrogance with power. She states that she knows "who, what and whose" Thomas Raith is before confirming that Harry Dresden's use of Summer fire brought all of the Winter Court to Arctis Tor.
When Harry Dresden tries to free her, Lea stops him and tells him she cannot be trusted. A personality struggle takes place within her and Harry leaves her behind.
- Main article: Changes
In Changes, the Leanansidhe lulled the vampire parts of Susan and Martin to sleep, possibly demonstrating a way to treat half vampirism. Lea claims that she was being treated for an ailment by Mab during her imprisonment. She told Dresden that she would safeguard his treasures that he left in her garden. At Dresden's request, the Leanansidhe gave him his mother's jewel containing all her knowledge of Ways.
Lea was present at the Stone Table when Dresden made his bargain with Mab to take up the Winter Knight's Mantle in exchange of strength, aid and time to save his daughter, Maggie. She reminded him of her warning to him years back to never let Mab bring him to the Stone Table. While there, she acts as interpreter for Mab since her voice would make his ears bleed. After the bargain is made, Mab assigns the Leanansidhe with the task of aiding Dresden on his quest—Mab said Lea may indulge herself.
Lea picks up Dresden in a limo driven by Glenmael and outfits Dresden and Susan Rodriguez for the quest and returns his stash which included Bob and the Swords of the Cross. the Leanansidhe goes on the quest with Dresden to Chichén Itzá to save Maggie. Thoward the end of it, she impersonated one of the Lords of Outer Night to aid Dresden in defeated the Red King. Lea arranged a Way back through Donar Vadderung that led directly to Saint Mary of the Angels where they started the quest.
- Main article: Ghost Story
In Ghost Story, the Leanansidhe was sent by Mab to continue Molly Carpenter's training in her obligation to his Oath of Fealty—she's training her in combat skills. Lea talks with Dresden's ghost while watching Molly Carpenter fight the Fomor servitors. Dresden makes her buy Molly Carpenter's breakfast. Sometimes, the Leanansidhe takes turns with Molly Carpenter and poses as the Ragged Lady.  Dresden recalls in vivid detail his battle with He Who Walks Behind. the Leanansidhe bargains with Dresden for the rest of the tale in exchange for three questions. Lea told Dresden about Corpsetaker for his second question. She couldn't answer him directly about "who killed him" so she gave Dresden's ghost three "true" answers despite "Eternal Silence"'s warnings.
- Main article: Bombshells
- Main article: Cold Days
In Cold Days, Molly Carpenter states that Auntie the Leanansidhe taught her the locations of ley nodes around Lake Michigan a few months prior. Harry Dresden gives the map to her to mark. It is mentioned that the ailment afflicting Lea was an Outsider entity called "Nemesis" with a mind controlling influence taking possession of who it inhabits. Mab can cure the Outsider taint given time and the willingness of the afflicted. As Maeve was not willing to change back to normal, Mab could not cure her like she did Lea.
Word of JimEdit
Lea serves as Harry Dresden's godmother because of a deal she made with his mother, Margaret LeFay, before she died. Not much is known about the deal other than that she was in a rush, so she wasn't as detailed as she would have wanted it to have been.
In Celtic myth, the leanan sídhe ("fairy mistress") is a fae or type of fae known for taking human lovers and providing them with artistic inspiration, at the cost of madness and an early grave.
- ↑ Grave Peril, ch. 5
- ↑ 2.0 2.1 Grave Peril, ch. 27
- ↑ Changes, ch. 46
- ↑ Jim Butcher 2009 Bitten by Books Q&A
- ↑ Grave Peril, ch. 6
- ↑ Grave Peril, ch. 9
- ↑ Grave Peril, ch. 21
- ↑ Grave Peril, ch. 22
- ↑ Grave Peril, ch. 28
- ↑ Grave Peril, ch. 29
- ↑ Grave Peril, ch. 33
- ↑ Summer Knight, ch. 2
- ↑ Summer Knight, ch. 11
- ↑ Summer Knight, ch. 23
- ↑ Summer Knight, ch. 32
- ↑ Dead Beat, ch. 08
- ↑ Dead Beat, ch. 21
- ↑ 18.0 18.1 Proven Guilty, ch. 39
- ↑ Changes, ch. 15
- ↑ Changes, ch. 30
- ↑ Changes, ch. 31
- ↑ Changes, ch. 38–39
- ↑ Changes, ch. 40-48
- ↑ Changes, ch. 48
- ↑ Changes, ch. 49
- ↑ Ghost Story, ch. 21
- ↑ Ghost Story, ch. 22 and 23
- ↑ Ghost Story, ch. 23
- ↑ Ghost Story, ch. 30–32
- ↑ Ghost Story, ch. 33 and 34
- ↑ Bombshells
- ↑ Cold Days, ch. 28
- ↑ Cold Days, ch. 51
- ↑ Jim Butcher 2010 Lee's Summit Signing
- ↑ Jim Butcher 2009 Chicago Signing