Character from Mage Errant by John Bierce
Hugh's sentient crystal spellbook — a mischievous merged entity of aether crystal, labyrinth stone, and spell book who can fly, store books in pocket dimensions, and has strong opinions about pinecones.
Mackerel communicates not through speech but through a bond with Hugh that conveys emotion, intention, and occasional strongly-held opinions about objects he encounters. He is mischievous in the way a clever pet is mischievous — drawn to things he shouldn't touch, prone to hiding objects he finds interesting, and deeply resentful of being ignored or left behind. As a merged entity of aether crystal, labyrinth stone, and spell book, Mackerel is something that shouldn't exist — a unique creation whose capabilities are still being discovered. He can create anti-scrying fields, store entire libraries in a pocket dimension accessible through his pages, and fly with enough speed and force to be genuinely dangerous. His dislike of pinecones and hats is well-documented and unexplained.
A book-sized construct of green crystal with a warm orange center that pulses like a heartbeat. Mackerel's surface is smooth and faceted, catching light in ways that shift with his mood — brighter when excited, dimmer when sulking. He hovers at Hugh's shoulder or tucks under his arm, occasionally spinning in place or darting around rooms with surprising agility for what is essentially a floating rock.
Also known as: Mackerel, Mack