WARNING: SPOLIERS FOR JOURNEY'S END :WARNING
A/N: I re-watched Journey's End, and thought this matter had be addressed. it was just eating me up inside! This story was orginally just the first two paragraphs, but I felt the rest of the scene needed explaining, and so this kinda ended up a lot more involved, and less funny than the orginal idea. But: MEH.
Always Tie Up Your Shoelaces, Kids
The Doctor slowly turned, squinting up the dark street, past the hulking shapes of abandoned cars. There she was, a blonde-haired figure slowly walking towards them. How had Donna even recognised her from this far away? It was impossible – it really was Rose!
A grin split the Doctor's face in two, and he began to sprint up the road, trainers pounding on the hard tarmac. But, the smile fell off his face when his foot refused to leave the ground, and he remembered all too late that he'd forgotten to tie up his shoelaces. The ground rushed up to meet him with a 'whoomph', and his face hit the ground, quite painfully by the looks of things.
The cry of "EX-TERM-I-NATE" came from a side alley, the shot from the Dalek's gun fizzing through the air right where his chest would have been if he hadn't tripped. The Doctor groaned and rolled onto his back as Jack appeared out of thin air, the blue bolt from his gun transforming the offending Dalek into various pieces of twisted metal scattered across the ground.
"You alright?" Rose asked as she reached the Doctor's side, genuine concern in her voice.
The Time Lord nodded as Jack helped him back to his feet. "Me? Yeah, fine." He grinned at Rose, and there was one moment of silence before they both ran to embrace each other. Jack watched the two old friends with his trademark Harkness-grin on his face, but Donna's attention was elsewhere. That voice, in her head … it sounded so familiar, almost … but it was darker than his, and it was telling her to do the unthinkable.
She leant down, and retrieved Rose's enormous gun from the ground. Could she really do it? Could she do as the voice in her head said? She didn't have a chance to ponder it, because her arms made the decision for her. They aimed the gun seemingly of their own accord, her finger curling around the trigger.
The Doctor and Rose had just finished their excessively long hug when the blue bolt stuck the Doctor in the side. He flew off his feet and into the door of a car, the metal buckling around him. Rose immediately rushed to his side, checking to see if he was alright. Jack, however, gently took the gun from Donna.
"I had to do it," she explained without needing any prompting. "If the Doctor isn't forced to pour his excess regeneration energy into his handy spare hand, I won't have a chance to cause a human-Time Lord Metacrisis, therefore causing Davros to completely destroy the whole of creation with single stream Zed-Neutrino energy!"
Jack gawked at her. "What?"
Donna stared right back at him. "Huh?"
"Zed what energy?"
Donna looked at him blankly. "What are you on about Jack?"
Their conversation was punctuated by a moan from the Doctor, and Jack was suddenly all business again. "We've gotta get him to the TARDIS!"
Donna paused for a few seconds. For a moment there, she was sure there was a voice in her head that sounded awfully like the … She shook her head. Never mind. It looked like the Doctor was in pain, and the best place for him was the TARDIS.
A/N: To explain Donna's reason for knowing about future events, I think the Metacrisis echoed back along the Doctor's time line when he didn't get shot (just like the Human Doctor's heartbeat did), and Donna knew that she had to fix events back to their orginal course. She then forgets about it ever happening, which is so very Donna. Gerh. That's just one theory though.