Standing inside the Master's TARDIS - getting the ship had been hard, but thanks to the dematerialisation circuit he'd stolen, it was easy to track down the main ship - the Doctor was carefully adjusting the controls, and was thankful he'd managed to steal the Master's TARDIS without the other Time Lord being aware of it.
The Master's TARDIS was starkly different from his own; where the Doctor's TARDIS was comfortably old, and shabby, there was a definite welcoming quality which had become more apparent as Ian and Barbara were replaced with Steven, Vicki, Dodo, and went on all the way to Jamie and Zoe, the Master's TARDIS was colder and more functional.
Fully operational TARDISes were not designed to show any emotion. That suited the Time Lords perfectly to a t.
But the Master's TARDIS was operational and he was relieved by that. As he was carefully setting the controls which would replace the Dalek Time Machine with the similarly sized block of high explosives which would blow up in place of the Dalek time capsule and fool his first incarnation into believing the timeliness were stable, the Doctor thought about the recent events.
Originally he had wanted to just dismantle the dematerialisation circuit and use it as the base for a crude time scoop, but when he had conducted the first trial run with the added components of the dematerialisation circuit from his own TARDIS, he'd had to abandon the procedure because the lash up had nearly exploded in his face, but luckily the circuit from the Master's TARDIS had survived.
When the Doctor had first arrived on the Earth, he had spent months trying to test how his knowledge of time travel and time technology had been limited by the blocks put on his memories by the Time Lords, and for the first time since his reckless experiments in building a Time Scoop, the Doctor finally understood the extent, and he was lucky that he'd managed to save both circuits before they fused completely before he decided to simply try to track down the Master's TARDIS when he put his mind to the task, realising reckless experiments were not going to cut it this time.
Besides, the last thing he wanted was for the Master to discover what he'd done and lose it.
He was even more pleased to say the circuit was working perfectly, and that the Master's TARDIS was taking him to where he wanted to go, and more importantly, without giving him any grief. Why hadn't he stolen one of those new-fangled Type-70s instead of the old rundown Type-40? Okay, back then the Doctor's first incarnation had been in a rush to escape the Time Lords, and believed the old TARDIS he'd taken at the last minute would do, being so arrogant to believe the old TARDIS he'd taken would be enough, and he'd never be caught.
He hadn't bothered even to take a backup time machine, like a Vortex manipulator.
As the Master's TARDIS arrived in 1964, easily following the time trail of the Dalek time machine as he crossed the timelines, the Doctor watched and waited as the time machine landed in a garage in London. He waited until Ian and Barbara left the time machine and got to safety, priming the detonator of the bomb, before he hit the controls; the TARDIS, obeying its earlier programming, materialised around the Dalek time machine, dematerialising around allowing the Doctor to rush inside the equally harsh lighting of the more primitive capsule, and he shut off the self destruct before he rushed back out, transmitting a pulse to the bomb, and it exploded.
The Doctor reset the controls for the TARDIS to take him back to the 1970s, and it dropped the Dalek time machine off in the UNIT labs before he took the ship back to where he'd left it. The Master's TARDIS had only been gone for 10 seconds, relative time. Once it had materialised and he'd checked the scanner, the Doctor was relieved to see the Master wasn't nearby, although what the other Time Lord was doing, he'd soon find out later.
-8-
When he arrived back at the UNIT labs, the Doctor slowly entered his laboratory and he grinned at his prize. He walked up to the Dalek time machine, remembering how it had recently, from the perspective of the machine, chased him, Ian, Barbara, and Vicki through the vortex before that final battle where its crew were killed by the Mechanoids.
The time machine was primitive. It was powered by taranium, but the Doctor was torn by what he was going to do now. He didn't know whether he should dash into the time machine, and travel to different places in time and space, or whether he should stay on Earth in the 20th century and take the time machine apart to make improvements to its systems.