Yuu rushed towards the Doctor, as he prepared to clamber onto Greseer's back.
"Doctor! What are you doing?" he cried, confused.
The Doctor turned back towards him, looking past him, to the grand house they had left so many hours ago, to the band of Samurai watching Greseer with nervous apprehension. His eyes blazed with a ferocity, determination clear in the his posture.
"General, it has become clear that trying to seal the breach like this is not going to work. Greseer here has persuaded his kin to stop stealing your Samurai's minds, but in coming back here, he has weakened the rift in time and space almost to the point of collapse."
The General stopped at a safe distance from the Tarkonian, still wary of the great beast. "So you're going to do what exactly?"
"I'm going to go with Greseer back through the portal to try and seal it from the inside."
Yuu glanced at the dragon. "Sacrificing yourself in the process?"
The Doctor moved towards Yuu, looking him straight in the eyes. "It's a risk I'm willing to take." As he whirled around again, he carried on. "And we've still got Clara, with the TARDIS."
The TARDIS wasn't exactly a First-Class aeroplane. It flung Clara about like a tree in a storm. But, also like a tree, she clung on to the console and stand standing.
"Where are you taking me?" she murmured. "What is the Doctor doing now?"
Something incredibly stupid but insanely selfless, she thought, as always.
The Doctor ignored Yuu's protests. He knew this looked like a suicide mission, and maybe it was. But he trusted Clara, and he knew his TARDIS. He had to do this, otherwise Earth was in danger of not having a future. Earth was extremely important to him. The people who inhabited it were worth saving. His eyes misted over as he remembered some of his more recent companions, and the love he bore them. Donna, with no memory of him; Martha, who had moved on from him; Amy and Rory, the love they found in each other leaving him alone; and Rose gone from his life forever. He wouldn't not let that happen to Clara. He had to save her, he had to save all of them.
With this in mind, he sat firmly astride Greseer's bulk, holding on for dear life as the dragon rose up with a flap of his magnificent wings.
"Are you... certain this...is...what you... want to... do, Doctor?" asked Greseer as he hovered just before the rift. From here, the Doctor could see how unstable it was - a blur of colour, whirling around, sparks occasionally lighting up the gathering darkness.
The Doctor gathered his nerves. He couldn't back out now. "Yes, Greseer. I am."
The dragon moved with surprising agility despite his great bulk. Before either of them could have second thoughts, he was flying straight towards the gap in space and time. All at once, they were surrounded by light, colour and noise. Disorientating and confusing. The Doctor quickly suppressed the doubts rising in his mind. He couldn't afford to lose his nerve.
"To infinity," he whispered, unaware of anything besides his heartbeats roaring in his ears, and the feeling of Greseer's rough hide beneath his fingers; unaware of his TARDIS and its passenger and their mission to save him.