Sorcery of Thorns

This fantasy novel by Margaret Rogerson is probably considered a YA entry, although the two main characters are in their 20's. Elizabeth Scrivener was taken into the care of one of the Great Libraries of Austermeer at Summershall when she was left on the doorstep as an infant. She has never known any other life. The books (grimoires) talk to her; they contain magic and secrets of sorcery. Some are fairly benign and others are so malevolent that they must be locked away in vaults to protect the populace. She is an apprentice when the story opens and wants nothing more than to become a Warden, i.e., an official protector of the Great Libraries. But someone has started attacking the Great Libraries and Elizabeth is the only one who wakes up when Summershall's wards are breached and the most dangerous of their grimoires is released, killing the library's Director. With the Director's sword, she manages to defeat the evil Malefict but is subsequently accused by a corrupt librarian of collusion in the attack and sent to the Magisterium for judgment. Her transportation is provided by Sorcerer Nathaniel Thorn and he looks cruel, and all sorcerers are evil, so Elizabeth has been taught. But he is kind to her, protects her from another attack by demons, and stands up for her in the Tribunal. Elizabeth doesn't know what to make of him. When she is taken into the home of the Master Sorcerer of Austermeer, she finds out that the attacks on the Great Libraries are being planned by him, to what end she doesn't know. He tries to have her imprisoned in an insane asylum, but she escapes and tries to convince Nathaniel to help her uncover the plot and defeat the perpetrator.
Elizabeth, Nathaniel, and Nathaniel's dedicated demon, Silas, are all fully drawn characters and the plot is intricate and well executed. This was an engaging and enjoyable read. Favorable review from Kirkus,