Marticide (short story)

 was the fourth story in The Boulevard: Volume One.

Summary
Godfather Cococyte wanders a part of the Boulevard of Alternate Brutalities taken from parts of Mars that never existed, unaware he's in a prison or who he was. His recorded crime: "Marticide", erasing all the many alternate versions of Mars and replacing them with a dead world.

In a flashback to the 1910s, the elderly French doctor who will become Cococyte wakens on Mars. His ship has crashed and killed the rest of the crew. He is confused how he has survived and that he remembers that he has travelled already to Mars on a ship repelled gravity. As he looks at the planet and sees it cannot possibly support life, he decides that the memories he has must have been dreams, no matter how realistic they seem. This is interrupted by the arrival of his English peer Professor Helvetius, now wearing a skull mask, and calling himself Godfather Avenir.

Avenir says he's here to recruit for "the War", but the doctor (who takes the alias "Cococyte", the name of a Martian faction he recalls) is distressed by the fact that the skull Avenir is wearing is from a creature that never existed, and yet is a skull of a creature from his dreams. Cococyte tries to prove rationally how it could exist rather than accept science fiction but, having no choice, agrees to join Avenir's faction. He laments that perhaps the Cococyte never existed at all, prompting Avenir to refer to the Martian Embassy panicking that the canals stopped existing; when Cococyte says there's no such embassy, Avenir agrees.

In the 1970s, the native Martian Zyln passes the Great Face, a giant human-shaped sculpture built to signal to Earth they were not alone, on his way back underground. Avenir arrives to warn him that Cococyte has become aware of the Great Face from human telescopes and is coming to have a look. Cococyte is unaware he's unstuck in time and that everything he observes, he collapses the possibilities of; because he is unable to accept anything that doesn't fit, contradicts, or seems paradoxical, or accept that he himself doesn't fit in, he will 'see' the Great Face is an optical illusion and thus it will have always been one. To Zayn's horror, Cococyte's observation will mean he and everyone he knows will never have existed. As Avenir watches, the area becomes dust.

Cococyte wanders along Mars remembering a human expedition to the dead world and a job he had there, wondering if this plausible past is a delusion as well. As he starts to realise life on Earth is just as implausible as Mars, Avenir returns to ask him to stop: his skull of a being that never existed is now a human skull. Cococyte collapses in despair at realising what he's done and Avenir tells him that, as free will does exist in this world, he can choose something different and prevent the end of other worlds as long as he admits he has committed a crime towards Mars. After first arguing his only crime was trying to understand the universe, Cococyte accepts guilt and agrees to be sent to the Boulevard as punishment. Faction Paradox keeps him locked away so he cannot be the end of the universe.

Characters

 * Godfather Cococyte
 * Professor Helvetius/Godfather Avenir
 * Zyln

Worldbuilding

 * Avenir is aware the First World War is coming and refers to upcoming battles France will suffer in.
 * The Great Face is the famous, a sand formation that resembled a sculptured face in low-resolution space probe photos.
 * Cococyte remembers earlier human missions to Mars than the implicit near-future one he later is involved in.
 * Avenir and the Faction refer to quantum physics to explain Cococyte's powers.

Continuity

 * Among the relics of old Mars are pyramids. (TV: Pyramids of Mars)
 * With his name, life underground, and description as being from a "proud race" (after a novelisation line of "once proud race"), Zayn is implied to be an Ice Warrior.
 * Multiple timelines of Mars once coexisted in unstable equilibrium. (PROSE: Going Once, Going Twice)
 * The Martian Embassy panics about the canals disappearing. (PROSE: The Book of the Enemy)
 * Cococyte has caused Earth to reach Mars far later than in his 'dream'. While this refers primarily to Doctor Omega and the 1900s visit to Mars, humanity has landed on Mars multiple times in Doctor Who future history that then are contradicted by real history: firstly in TV: The Ambassadors of Death, then in PROSE: The Dying Days and AUDIO: Red Dawn.