Lasciel

Lasciel, also known as the Seducer, the Webweaver, and the Temptress, is a Fallen Angel and a member of the Order of the Blackened Denarius. She first appears in Death Masks.

Description
She seems to be a black sheep among the other Fallen; "a rebel angel among rebel angels." As such, she isn't trusted by Nicodemus Archleone and her coin isn't given to people lightly. Father Forthill comments that it was very odd that Nicodemus would want to free her (by giving her to Harry Dresden) since she does not follow Anduriel's lead.

In Small Favor, Nicodemus comments that Lasciel was the perfect coin for Harry, suggesting that she was the only Fallen who had a chance to turn him. Her nickname of "The Temptress" and "The Seducer" appear to be well-earned, as Harry constantly has to remind himself what she really is whenever she manages to connect with him or make him sympathize with her.

The sigil on her coin is "vaguely suggestive of an hourglass". The coin was supposed to be in secure storage in a Chilean monastery. Yet, it is in Nicodemus' possession to toss at little Harry Carpenter.

Death Masks
In Death Masks, Nicodemus tosses the coin in front of toddler Harry Carpenter just as Harry Dresden was walking up to the child. Harry Dresden's subconscious decides to pick up the coin instead of picking up kid, and he buries it in his lab within his circle under concrete surrounded by a powerful binding spell.

Dead Beat
In Dead Beat, at Bock Ordered Books, Harry Dresden encounters "Shiela" who seems to have perfect recall and helps him find Die Lied der Erlking ; Bock seems nervous at the interaction. She later calls Dresden saying she is scared so he meets her at Bock's again; Bock appears frightened as they talk, and tells Dresden not to come by anymore. That night, after using Hellfire, Harry has an odd dream with a hot tub set in a cave. Lasciel appears to him and explains that now that he has used some of the power she offers, she is able to interact more directly with him. She makes him an offer to aid him in fighting the Necromancers by teaching him secrets of his craft unknown to mortals. Harry sees through her offer of Power and declines.

Later, Harry meets Shiela at her apartment and has her recite the entire Erlking book for Harry by memory at her apartment in an attempt to discover the summoning ritual. Afterward, they kiss. As he prepared for his battle against the Heirs of Kemmler Harry returned to Shiela's place with Waldo Butters to check on her. When Butters comes in, he asks Harry who he is talking to; realizing what was happening, Harry used his Sight and discovered that Shiela was an illusion that Lasciel created so that she could help Harry, fearing that the death of Harry would mean the death of part of her. She claimed that she intended to reveal the truth to him afterwards, but she didn't want him distracted.

Proven Guilty
In Proven Guilty, Lasciel is still attempting to persuade Dresden to take up the coin. She offers him assistance in his investigations, but Harry won't allow her to influence him. She also points out the similarities between Nelson Lenhardt, Molly Carpenter's boyfriend, and Dresden.

White Night
In White Night, Dresden has taken to calling it "Lash". Lash is a separate character from the "real" Lasciel at this point in the series.

Harry talks about temptation and choice with Lash. He suggests that maybe being inside of him has had some effect on her, just as she has had some effect on him. When Lash is taken back into the whole, she will be gone: die. He then plants the seed that Lash has free will, too and that she can choose for herself, have a life outside of Lasciel.

In the battle of the Deeps, during Vittorio Malvora's crippling attack of despair, when Dresden and his friends about to be overrun by ghouls, and a bomb is about to go off, Lasciel speeds up his mind to effectively slow down time. She makes a bid for him to call the coin to him—he refuses, and asks her to help him instead. Lasciel initially refuses, pleading with Dresden that Lasciel would never forgive her, never take her back, if she failed here. Realizing that Dresden would rather die than summon Lasciel, Lash concedes that she has a choice and finally separates fully from Lasciel, saying that "I-she doesn't deserve you." Then, she tells him that Vittorio Malvora is possessed by an Outsider. Due to the circumstances of his's birth, he has the potential to wield power over Outsiders. Dresden can shake off the spell and she will give him the opportunity to do so. Then, she walks away toward Vittorio.

Lasciel's coin was given to Father Forthill in White Night, who placed it with the rest of the coins the Knights of the Cross had collected. At some unspecified point afterwards the Coin vanishes.

Small Favor
In Small Favor, Michael Carpenter is suspicious of Dresden because of Lasciel. When Dresden confronts him, Carpenter points out that nobody has ever gotten rid of the shadow of the Fallen without summoning the coin, and notes that he has never told him how it happened. Harry just tells him that it wasn't fair what happened to Lash.

After the attack on Demonreach, Nicodemus Archleone attacks Dresden, and comments on his surprise that Dresden hasn't taken up the coin in spite of the years Lash had to reason with him. He then orders the shadow to incapacitate him, not knowing that it was gone.

Skin Game
In Skin Game, Lash's death results in a spirit of intellect growing in Harry's brain, with all the knowledge and power of both Dresden and the Fallen Angel but without any idea of what to do with it; without proper guidance, the spirit could be very dangerous.

After Nicodemus betrays Dresden in Hades' Vault, it is revealed that Lasciel was back and using Hannah Ascher as her host. She is motivated to kill Dresden by both her desire to save her child and her pride by his refusing her; according to her she had never been rejected before. She also claims to be the shadow who whispered in Dresden's ear the words that caused the events in Ghost Story. She guides Hannah in a battle with Dresden, who pleads with Hannah to break away from Lasciel, but Hannah ignores him and attacks with a blast of fire. Dresden blocks the blast and sends it into the ceiling, then falls on his knee with a shield in front of him; Hannah thinks he's finished, but Lasciel's eyes widen as she realizes what he had really done. A second later, flaming debris from where the attack hit the ceiling drop directly onto Hannah, killing her.

After Hannah's death, her coin is stuck in Hades' Vault.