The Constant Doctor (short story)

The Constant Doctor was the fifteenth and final short story of The Scientific Secrets of Doctor Who, featuring the Fifth and Twelfth Doctors.

Summary
The Fifth Doctor, Adric, Nyssa, and Tegan arrive on Lemaria to discover they have arrived during a Lemarian holiday, Freedom Day, the day when the Lemarians were freed from the tyranny of the Megrati. The group is invited to watch a reenactment of the liberation. On the way, they spot a mural that depicts the liberation. To their shock, an image of the TARDIS is on the mural, along with the image of the First Doctor. The Fifth Doctor, however, doesn't recall his previous visit. He isn't concerned, though, as he's saved a lot of planets, and this incident took place a long time ago for him.

The four find seats for the performance. They watch as the performance plays out. When it gets to the part about the Doctor's arrival, the Doctor notes that the TARDIS prop was very well done, despite not being fully accurate to how the TARDIS used to look. At that moment, the actor portraying the First Doctor steps out from the TARDIS, along with the actress portraying Susan Foreman, shocking the Fifth Doctor's companions, as they didn't know the Doctor had a granddaughter. The Doctor quickly avoids the topic by going to get some food, leaving the three companions to talk to each other, realising how little they actually know about the Doctor. They then start talking about regeneration, about how each of them was affected by the Doctor's most recent regeneration, and wonder about how the Doctor views the process.

The Doctor returns with the food, telling them that he now remembers his previous visit. As he recalls, it didn't take him long to liberate the planet. There was already a resistance group, when he arrived, and all he did was give them a helping hand. The four go back to watching the play, but the Doctor is curious about how good of a copy the TARDIS prop is of the real thing. They also notice that the actor playing the First Doctor has a Scottish accent.

The play ends and the actors take their final bow. The stage Doctor notices the four in the audience and smiles at them. The Fifth Doctor tips his hat to the stage Doctor, having realised the truth about the actor and the TARDIS prop.

At that moment, a fleet of Megrati ships arrive, and the leader teleports onto the stage, wanting to know who summoned him here. The stage Doctor steps forward, revealing that he had detected the invasion fleet on its way, and had sent the invitation so that he could have a chat with the leader. The Megrati leader tries to attack the stage Doctor, but the man disarms the leader. The stage Doctor tells the Megrati leader to take his fleet and leave, or have his ships destroyed.

The Megrati leader doesn't believe that the stage Doctor can stop him. However, the stage Doctor pulls out a sonic screwdriver and uses it on the crystals in the Megrati command ship's engines, destroying the ship slowly enough to allow the crew to evacuate to other ships. The use of the screwdriver is enough for Nyssa to realise that the actor is no actor, but is an actual incarnation of the Doctor.

The Twelfth Doctor once again demands the Megrati leader to leave. Seeing no other option, the leader decides to leave. Before he teleports away, the Doctor warns him to never return. If he does so, the Doctor will wipe out the entire fleet. As the crowd watches the ships start to leave, they start shouting at the Doctor to finish the job and destroy the other ships. The Doctor turns to the crowd, and gives them an angry look, asking them if that is what they really want. He even offers to let one of them take the screwdriver to deal the killing blow. No one moves or says anything, so the ships are leaving, and so is the Doctor.

The Doctor walks over to his TARDIS, telling the crowd he will go make sure the Megrati leave this star system, and tells them to get back to celebrating. Nyssa is happy to see this, knowing that no matter how much the Doctor changes, he will always be the Doctor. The Twelfth Doctor takes a final bow. With one last look and smile at the Fifth Doctor's group, he steps into his TARDIS and departs.

Characters

 * Fifth Doctor
 * Twelfth Doctor
 * Adric
 * Nyssa
 * Tegan Jovanka

Worldbuilding
to be added

Continuity
to be added