Mycroft Canner is our chronicler and author of the "explanation of those days of transformation," as depicted by Too Like the Lightning and Seven Surrenders. After the Days of Transformation, Mycroft continues his account of history in The Will to Battle, commissioned by J.E.D.D. Mason to document the war's beginnings. He is a Servicer, condemned to a life of public service for crimes committed as a teenager.
Mycroft's Servicer uniform is described as "dappled beige and gray." He has dark, overgrown hair, and skin that is "a little dark." His registered possessions include two changes of Servicer uniforms, one pair of non-regulation boots (fitted with brushes on the soles as to prevent the crushing of bugs), one non-regulation cap (gifted to him by Dominic Seneschal), and Apollo Mojave's Illiad.
Mycroft bears multiple affiliations and serves many masters. Over the course of the Days of Transformation, Mycroft is seen to run errands or otherwise serve the Saneer-Weeksbooth bash', Chief Director Ando Mitsubishi, Humanist President Ganymede Jean-Louis de la Trémoïlle, Emperor Cornel MASON, Censor Vivien Ancelet, Utopia, and Madame D'Arouet. These duties of service to every major world power is Mycroft's lifelong debt for having deprived the powers of someone of commensurate value over the course of their crimes.
In The Will to Battle, Mycroft attempts to swear an oath of allegiance to Achilles; Achilles does not allow them, citing too many allegiances.
Mycroft's childhood bash was killed in an explosion when they were eight. Mycroft had a ba'sib named Saladin. They were later taken in by the Mardi bash, where they received education and mentoring from Aeneas and Kohaku Mardi, as well as Apollo Mojave.
Mycroft is best-known for perpetrating the "Canner killings" or "Mardi Massacre": a bloody, two-week, seventeen-victim rampage which effectively destroyed the Mardi bash' and their friend, Apollo Mojave. The sole survivor of the massacre, Tully Mardi, survived by taking Apollo Mojave's seat on the ship to Luna City, where they would survive under Utopia's protective custody.
Mycroft's stated purpose for perpetrating such crimes is unclear. They have previously said that they wished to cause the greatest deliberative body in humanity's history to contemplate capital punishment. At other times, they muse that they killed the Mardis so gruesomely to show that humanity is still capable of diabolical evil. In Seven Surrenders, in a conversation with Emperor Cornel MASON, Mycroft states that they killed the Mardi bash in order to prevent the Mardis from starting their war.
Mycroft speaks multiple languages, highly unusual in Terra Ignota. While everyone throughout the world is expected to know the Common Tongue, English, other languages are reserved for specific hives or nation-strats. Mycroft speaks English, Latin, Spanish, French, Japanese, Greek, and U-Speak. They learned many of these languages in attempts to ingratiate themselves with various members of the Mardi bash.
It is also implied that Mycroft has the cognitive and calculative capabilities commensurate to a Cartesian set-set. In Too Like the Lightning, Martin Guildbreaker's investigation requires a Cartesian set-set. However, before Guildbreaker hires a set-set, he first asks for Censor Ancelet to run the calculations, who was too busy, then asks Deputy Censor Su-Hyeon to run the calculations, who was too busy, and then Mycroft, also too busy. Vivien Ancelet also describes Mycroft as one of the best statistical analysts in the world, and in Too Like the Lightning uses Mycroft to help predict the Seven-Ten Lists's impact on society.
It is also hinted that Mycroft has some proficiency in some form of hand-to-hand combat. In Seven Surrenders, Mycroft recounts many an afternoon sparring with Ojiro Sniper. The two (or at least Sniper's doll) exchange real blows, with the intention to harm, in Seven Surrenders.
Mycroft is known to have a pacemaker, used to treat an irregular heartbeat and generally questionable cardiac health. Mycroft is known to manipulate these cardiac irregularities as a means of tricking and slipping their tracker, effectively allowing them to disappear for periods of time. He has had open heart surgery at least two times. In a conversation with Papadelias in Seven Surrenders, it is revealed that the first surgery was conducted by Saladin while the two were still in their teens.
Mycroft has also been declared criminally insane. This certified lack of mental capacity is what allows Mycroft to write the history of the war in The Will to Battle, as any testimony Mycroft produces would be inadmissible in a court of law. J.E.D.D. Mason uses this status to guarantee that world powers would be willing to respect Mycroft's independence as a chronicler, and thus aid in preserving a truthful history of unfolding events. 9A, in notes and asides in The Will to Battle, notes that Mycroft has been insane throughout his chronicles, beginning in Too Like the Lightning. However, it is only in The Will to Battle does this insanity become impossible to contain or edit out. Mycroft's insanity manifests in hallucinations, often as imaginary conversations with Apollo Mojave.
Mycroft's body is also riddled with innumerable scars. In spars with Sniper, Mycroft reveals the stories behind any given scar about one third of the time. One of Mycroft's identifying characteristics is a missing two and a half centimeter portion of their right ear.