Mermaid

Appearance
Petite, with dark-green eyes and "Hair the color of milky coffee, falling below the knees" (by Tabaqui's reckoning; Sphinx says "almost to her knees"), into which she braids small bells. Previously a wheeler but now walks.

Notable Relationships

 * Sphinx
 * Tabaqui

Before the House
Anticipating Sphinx's decision to go into the Outsides after the graduation, Blind devises a scheme to influence it: during one of his visits to the Master of Time he asks for and receives a mermaid egg, which he then hatches and brings with him without allowing it to fully mature. Mermaid appears in the House as a girl who looks smaller than her "age" and has some difficulties using her legs. In their last conversation Blind then explains to Sphinx that "She is of another world, there is no place for her in this one". While initially resentful, Sphinx comes to realize that Mermaid was indeed a gift of the House, "given to me in the hopes of holding on to me when the time came, only with that, not by force or deceit".

In The House
Mermaid lives in the "Dreadful Dorm" with Catwoman, Ginger and Rat. Mermaid has already been in the House at age 8 - that is, before the seniors' graduation. We only get to see her after the Law, but her chapter fills us a bit on her past - that she used to do physical therapy for her legs, and that she became good at knitting. We also learn that she is in love with Sphinx; she tries using magic to make herself attractive to him (by stealing Ancient's amulet from the nightstand and adding a lock of her hair to it) and acceptable to the rest of the Fourth (by acquiring things that belonged to each of them and carrying them with her everywhere). The sorcery works: in Book 3 Sphinx and she are romantically involved, and she often spends nights in the Fourth. Mermaid also takes an active interest in Tabaqui's stories and his quest to collect "no one's things".

Epilogue
Mermaid accepts Sphinx's choice not to move to the Other Side and appears to be taken away after graduation by an elderly couple whom Smoker thinks to be her parents. Sphinx then fails to find them, as the address they give him turns out not to exist. After visiting the ruins of the House and finding there a small bell tied to the tail of a picture of a fish, he returns to his apartment to find Mermaid waiting for him there.

Allusions

 * "The Little Mermaid" by H. C. Andersen. The Little Mermaid sells her hair and voice to the Sea Witch in exchange for human legs (which are still extremely painful to walk on). No such sacrifice was heeded here, except for the physical therapy. The chapter in Book 2 titled "Sorcery" has in the original an epigraph from the tale: “Yes, I know what you want!” Sea Witch said. “And it is very stupid of you!”.
 * The story of Orpheus and Eurydice. Sphinx comes to the remains of House and makes peace with its influence in his life, which allows him to take Mermaid with him to the Outsides.
 * The story of Proserpine (Persephone, Cora). Smoker remarks that "one day she’s there with [Sphinx], the next day she isn’t anywhere, and her disappearances can last for months". It would appear that since Mermaid is not of this world, she cannot exist in it constantly and needs to go back at regular intervals - just as Persephone needs to spend part of the year in the netherworld.

Sirène