The Wings of a Butterfly (audio story)

The Wings of a Butterfly was a 2010 audio short story written and performed by Colin Baker for Big Finish. It featured a companion-less Sixth Doctor. Written about the year 2000, and previously published in the unlicensed anthology, Missing Pieces, the story explored the Doctor's willingness to change the flow of time in ways not authorised by the High Council of the Time Lords.

Summary
Visiting Gallifrey to attend an academic conference, the Sixth Doctor's old friend and mentor, Duotheros, requests that he use the TARDIS to examine a temporal anomaly centred on Bixor. The planet, once thriving, appears to have mysteriously eradicated itself, substantially reducing the number of people interested in buying Duotheros' definitive history of that sector of space. Will the Doctor's investigations reveal the cause? Or does Bixor's untimely demise have something to do with a certain blue box?

Plot
After giving a presentation at the Time Lord Academy, Duotheros invites his former student, the Doctor, to his study quarters to ask him a favour. Duotheros had been studying the history of the planet Bixor, when it was suddenly destroyed by an unknown event on the planet. As the Doctor was less inclined to ignore the mystery of the planet's destruction, compared to other Time Lords, Duotheros had decided to ask the Doctor to head to Bixor to discover the cause of its destruction. The Doctor agrees to the request and departs. Duotheros thinks about what he has just done, and, considering the Doctor's tendency to get involved with things he shouldn't, quickly changes his mind, heading to the door to call the Doctor back. Upon opening the door, he finds out he is too late, for standing outside the door is the Doctor, having just returned from Bixor. The two step back into the study.

The Doctor explains what happened to Bixor. Its destruction was caused by a incorrectly made pair of trousers. A man had been wearing the trousers while walking on a crowded street, when the trousers fell down. People noticed and stopped to laugh at him. While they were all distracted, a pickpocket stole keys from the pocket of one of the laughing people. Upon discovering the car the keys belonged to, the pickpocket gave his bicycle to a nearby boy, before driving off in the stolen car. The boy, not used to riding a bicycle, was unsteady on it, and accidentally rode it out into the road, into the path of a large truck. The truck swerved to avoid the boy, accidentally crashing into a substation, causing a power outage to an entire manufacturing sector. It took hours for the damage to be repaired.

One of the facilities affected was a vector module assembly plant. When the power was restored, the machinery in the factory sprung back to life, implanting sixteen modules with double printed circuits, which were subsequently installed into the guidance system of an aerial transport drone. The drone's function was to transport dangerous materials to the capital's central nuclear power generation plant. The drone's main system developed a fault, leading to the activation of the backup, double printed modules. When this occurred, the drone was flying over Bixor's only active volcanic fissure. The drone accelerated to sub-light speed and dove into the fissure. The dangerous materials reacted with the planet's magma, causing a chain reaction that destroyed Bixor.

Duotheros is shocked upon hearing this. For Bixor, a world whose inhabitants were supposed to create great things, to be wiped out thanks to a pair of trousers is horrific. The Doctor offers to travel back to Bixor to make a "trouser adjustment". As the destruction of Bixor has only just been discovered, the record of the event hasn't be uploaded to the Matrix yet, so the Time Lords won't know of him making such a change. Duotheros thinks about it and decides to take the risk.

Upon returning to Bixor, the Doctor discovers why the trousers were incorrectly made, and swears to never do a favour for any old friends ever again. The trousers had been incorrectly made, because the worker who created the trousers had been distracted by a sight outside her window, the sight of the Doctor's TARDIS materialising outside the building. She had witnessed the Doctor's original arrival to Bixor, and it had been the Doctor's arrival to discover the cause of Bixor's destruction that had actually been the cause of its destruction.

Knowing this, the Doctor travels back in time 30 years before his original arrival. He then plants a tree outside the building, one that would grow and block the window, preventing the worker from being distracted by his arrival resulting in the trousers being correctly made, averting the destruction of Bixor. The Doctor heads back to the TARDIS, only to discover something horrible. He had parked the TARDIS near another manufacturing plant, and multiple workers were staring out of their windows at him, meaning his second arrival had also been witnessed and had distracted some workers.

The Doctor knows he can't risk that this event could once more lead to Bixor's destruction, so he decides to take no chances. He travels back in time one day, in the middle of the night, away from any building. He then walks back to the site of his second arrival and sets up a series of mirrors to obscure the spot where the TARDIS will appear, preventing the workers from seeing his arrival. Upon finishing, the Doctor returns to the TARDIS and departs, heading back to Gallifrey. Upon arriving, he is greeted by Duotheros, who has no recollection of the timeline in which Bixor was destroyed, or of having met with the Doctor anytime recently.

Characters

 * Sixth Doctor
 * Duotheros

Worldbuilding

 * The word Tellurian is used to indicate "Earth-like" or "from Earth".
 * The Doctor feels like he's playing a long game.
 * Duotheros has studied the rim galaxies.

Continuity

 * The Sixth Doctor's attitude towards changing history is the polar opposite of that expressed by the First Doctor. (TV: The Aztecs)