This is set during book seven, when Ron can't stand it anymore and leaves the tent. He never reached the Snatchers.
Ron stormed through the snowy woods, hunger gnawing painfully inside him. Slowly, Hermione's desperate cries faded. He had no plan, no idea what to do next. The Horcrux was no longer affecting him, but the weeks of cold and hunger were.
He walked until his feet were numb, until his nose and ears were burning with cold. "Thought you would've had a plan," he muttered furiously. "Not camping out in the freezing woods for weeks, eating stuff that can barely pass as food."
A loud, unfamiliar noise startled him. Ron yanked out his wand as a rectangular object materialized directly in front of him. Even after growing up in the magical world, Ron didn't know what to make of it.
"Who's there?" Ron asked, realizing too late that it probably wasn't a good idea to draw attention to himself.
A door creaked open, and as Ron stepped back, someone came into view. They closed the door behind them, extinguishing the thin sliver of light. Once more, Ron was standing in darkness.
"Lumos," Ron muttered, and the tip of his wand lit up. The other person became visible. Ron's first, wild thought was of Xenophelius Lovegood, though this didn't last long. The man before him had shorter hair, and was dressed like a- a-
"A muggle," Ron gasped. "Nox," he added, extinguishing his wand.
"A what?" a voice asked, coming from the direction of the man. "Were you talking to me?"
Ron didn't know what to say, and was saved by the door opening again.
"Grandfather," a girl's voice said, "where are we? Why is it so dark?"
"I'm not sure, my dear," the man replied. "Hold on..." moments later, the door opened completely and light sparkled off the snow in the clearing.
It only took Ron a few moments to realize that the object was a police box, similar to the guest entrance to the Ministry, only blue. His next realization was that the box was bigger on the inside. Having had many experiences with this, however, Ron wasn't fazed. "Undetectable extension charm?" he asked knowledgeably.
The man's expression was, if anything, disappointed. "You're not going to say it's bigger on the inside?"
Ron shrugged. "A lot of things are – our tent, for one."
Leaning forward slightly and balancing his weight on his cane, the man studied him more closely. "Have we met before?"
"I don't know," Ron answered. "I can't think well when I'm hungry. Do you have any food?"
Half an hour later, Ron, the man, the girl, and two others were all walking towards the tent.
"I'm the Doctor," the man said, now visible by the light of Ron's wand, "and this is my granddaughter Susan-" he gestured to the girl, "Barbara-" he pointed to the other woman, "And Ian," he finished, inclining his head towards the man.
"The Doctor?" Ron repeated. "Like one of those muggle nutters who cut people up?"
"No, just the Doctor," he responded. "But there is a more pressing question," the Doctor continued. "What is that?" He pointed to Ron's glowing wand.
"My wand," Ron said, having lost all suspicion that this man could be a muggle.
The Doctor opened his mouth to reply, but was interrupted by Ron.
"We're here," he said, pointing to the tent. He could hear Hermione's voice inside.
"Where?" the man called Ian asked, looking around. The others were also staring blankly. Clearly, Hermione's enchantments had worked.
Ron led them inside the ring of magic, at which point the group seemed to stiffen.
"But it was... invisible," Barbara murmured, staring at the tent. "How?"
"The universe is a strange place, my dear," the Doctor said, looking to Ron. "After you?"
The moment he entered the tent, Ron found himself being strangled by Hermione. "Can't- breathe-" he managed to gasp, and she released him from her hug.
"Ron!" Hermione exclaimed, wiping tears from her red-rimmed eyes. "I was so worried!"
"I, erm, brought guests," Ron said, looking back at the tent flap as the other four entered. Used to traveling in a TARDIS, they didn't exclaim over the interior.
"Are they muggles?" Hermione demanded in a hushed voice. "Who are they? Ron!"
"They're not muggles," Ron said quickly. "At least, I don't think so. They just appeared. In this... phone box... thing!"
Hermione looked up. "I'm sorry. Who are you?"
"I'm the Doctor," the Doctor introduced. "And these are my companions Ian and Barbara, and my granddaughter, Susan."
"Why did Ron bring you here?" Harry asked, from where he was seated in the corner.
"He claimed that your tent was – as it indeed is – bigger on the inside. If I may?" he took a small step forward.
Hermione and Harry exchanged a glance.
"I... guess so," Hermione finally said.
The Doctor conducted a brief examination of the tent. "It is most curious," he said, "but I can't seem to find a console. Don't you have one?"
"A... a what?" Hermione asked, obviously flustered. "Wh- whatever for?"
"To steer the ship, of course!" the Doctor exclaimed. "Don't tell me you let her steer herself?"
"What ship?" Hermione inquired, frowning at Ron.
Ron threw his hands in the air, having no more idea than the rest, as the Doctor finally asked, "This isn't a TARDIS?"
"I don't even know what a TARDIS is," Hermione exclaimed, her expression confusion bordering on irritation. "If you could please explain who you are, what you're talking about, what a TARDIS is..."
The Doctor took a deep breath, then began.
A/N: This is a one-shot, unless there's interest in another chapter. I love writing Doctor Who/Harry Potter crossovers, and I love getting reviews when I post them! ;) please review!