A/N: At some point in this story, there are going to be similarities between this story and Ace of Gallifrey's incomplete "All The Way Home" - I wish you had managed to complete that, Ace of Gallifrey, which is why I'm doing this! Nevertheless, thanks for the idea, Ace!
Additional: This is Part I of my "Crimson Cub" saga.
Prologue
She first caught sight of the TARDIS – that old girl, she thought fondly – parked on top of a hillside near Pompeii in 79 AD. She took a contemplative gaze at the Doctor, his new companion and a Roman family staring in shock at the destruction. She wished she could do something about it, but Pompeii was a fixed point in Time and Space – it could not be changed, and even if it could, she wouldn't be able to do anything; she didn't have the power to stay in her home Universe for long. Because she had been using a Charged Vacuum Emboitment, she had managed to avoid causing any Spatiotemporal scarring. But the power for the Cosmic Projector was limited, and she was now being pulled back to the pocket Universe she had inhabited for so long...
*DW*
She was watching a truly terrifying spectacle using a Quantoscope – a device she had devised to predict possible futures and analyse alternative Timelines. Every star in this Universe was being dissolved and extinguished – by a flattened wave of Zed Neutrino Energy. What made it worse was that the wave's point of origin was not coming from this Universe, but from her home Universe. Upon further analysis, the point of origin was confirmed as the Medusa Cascade, 2009 AD. But what could be hiding there? She had to investigate...
She wouldn't be able to take K-9 with her, and she couldn't leave her son behind. Part of her was terrified of what could happen to him, but another part acknowledged that he was capable enough to free the Tharils from enslavement. And besides, she knew that he wouldn't take no for an answer, if he was anything like his father...
*DW*
The Time Lady and her son, Jonathan – an Earth name she gave him in honour of his father's love of that planet – had packed the necessary equipment; Sonic Screwdrivers, Spacesuits, Artrometers, and stasers. Both of them hated weapons and hated having to use them – but it would be foolish to assume that whatever was capable of destroying Reality was not a ruthless killer. They powered up the Cosmic Projector that would take them both to N-Space, the Medusa Cascade, 2009, and felt a whoosh as they were shot across E-Space through the CVE...
...and landed right on target. Upon looking upwards, they found that there was no Sun, yet people were still running and screaming. An Atmospheric Shell, the Time Lady surmised. She turned to her son.
"Jonathan, I think it's safe for us to remove our helmets," she called to him over the Comm. "We're just standing here, looking ridiculous."
"I hear you, Mother," he replied, before moving to remove his helmet. His mother soon removed hers straight afterwards. When they had both removed their helmets, Jonathan continued. "I think we'd better set up camp somewhere. We don't want whatever we're up against to find us yet." He grinned a toothy grin that reminded her of the Doctor when she'd travelled with him.
She just nodded. What they were up against was obviously very powerful, and somehow, she knew that the nightmare was only just beginning...