"Nora!" The Doctor swept the screwdriver over the control panel. "Be careful! The Sontarans have a little bit of a thing about their carefully planned invasions being muddled around with!"
The short blonde kept her confiscated Sontaran blaster trained down the corridor. "Would a 'thing' be short for 'going sheer bloody psycho'?"
"Possibly! Most likely! Teensy bit of an overreaction, I mean, trillions of lifeforms swearing a blood vendetta against a single individual. My theory is that it's eons of collective repressed anger at all the short jokes."
"But everything's okay, right? You fix the last connection, we jump into the TARDIS and we're off!"
"Yes! Exactly! Nothing can go-"
Nora sent a volley of energy blasts down the corridor. The bolts hit the light-cloaked Sontarans, who had traded their normal armour for far weaker stealth uniforms, sending them crashing dead to the ground.
The Doctor finished his last connection, and got up, staring at the dead Sontarans.
"Nora! That was a full squad of Sontaran Stealth Elites trained in visibility minimisation and extreme tippy-toeing. How did you get them all?"
Nora hefted her blaster and tried to look as much like Linda Hamilton as possible. "As soon as you said 'Nothing Can Go Wrong' my finger just held down the trigger."
"It's like you're tempting God whenever you say that, or going into a pub after a match and pouring a pint down the pants of the biggest meanest-looking bloke there ..."
One Sontaran, clinging to the last dregs of life, raised his Rheon Carbine, sighted with a trembling hand -
"... and I'll continue with every analogy for taping a big bullseye to your shirt and shouting 'Come On Then If You Think You're Hard Enough' once we're safe on ..."
- and fired. The particle stream hit the female dead in the abdominal region, stopping her infernal prattling. Unfortunately, he couldn't properly appreciate his victory as he was quite dead.
The Doctor caught the wide-eyed body of Nora as she slumped into his arms.
He should be feeling something in response. Anger. Despair. Misery. But his emotional response could only be summed up in three words.
Oh Not Again.
The Doctor carried Nora's body into the TARDIS, setting dematerialisation and temporal orbit before heading towards the medical bay.
Laying her body on a stretcher, he selected a laser scalpel, and started cutting.
The smell was ignored as he removed the top section of her skull. The sounds were filtered away as he sliced between both hemispheres and retrieved what he was looking for.
A small metal sphere, the size of a marble, dotted with green flecks.
The Doctor turned towards a glass tank filled with murky fluid. The sphere was carefully placed into a set of metal clamps, which automatically lowered into the fluid. Already a cloudy material was beginning to coalesce around the sphere. With the ease of long practice, his fingers made the settings automatically. The readouts showed no surprises; neural patterns were interfacing, restructuring biological memories with a 0.0009% error rate. Nutrient feed and tissue growth stable. Rebirth in an hour.
This was being responsible.
The Doctor had long ago realised that he needed someone around. To talk to. To interact with.
To stop him.
He'd been alone for a while, ankle-deep in his own guilt, after taking a long and frank look over the course of his lives, and realising there were very few fellow travellers that he hadn't damaged in some way or form. Injured, hurt, crippled.
The idea, once it took place, rooted deep in his forebrain and would not be dislodged.
The sphere was comparatively simple to design and create. An indestructible quantum locked exterior. Bio-Compatible memory storage with millennia of capacity, with multiple neuron ports.
Human genetic samples were easy to come by. Mix and match, pick the best bit, go over a few times to debug, some randomisation for variety.
Okay, he tweaked some bits. Curiosity, just a little. A few necessary blank spots in perception.
Throw the switches, put on the kettle, and one very loud little baby after his third Jammy Dodger.
The Doctor stayed long enough to drop the baby off at a reputable orphanage, and making sure a decent couple picked up the child.
Forward nineteen years. One fairly bright but bored Nora Imogen Booth took one look at the TARDIS and was hooked. Taking it on herself to look after the vastly older Doctor but deep down, enjoying it just as much as him.
Never wondering on the odd occasion, she'd wake up in the medical centre sure that she'd met her maker, but the Doctor assuring her that her injuries had been easily treated.
Never wondering why she would be dressed in different clothes after those odd occasions.
Never wondering why she'd been travelling, without aging, for fifty-seven years.
The Doctor swept his sonic screwdriver over Nora's old body. The cellular structure broke down, and a grey syrupy mess slopped down the gaps in the stretcher and into the drains underneath the floor. Her old clothes were thrown into a molecular furnace.
This was being responsible.