A random fanfic I thought of when I was rereading the Half-Blood Prince and I thought maybe the Doctor and Tonks aren't very different. It takes place after the scene where Tonks has found Harry on the Hogwarts Express, lying underneath the Invisibility Cloak with a broken nose. She has taken him back to Hogwarts and meets, to her dismay, Snape at the gates. This is what happens afterwards, from Tonks's point of view. It's probably not very original, but it was mostly just for fun. Anyway, I hope you enjoy it.

"And incidentally," Severus sneered, his dark beady eyes piercing Tonks from the top of his beaky nose, "I was interested to see your new Patronus." Contempt poured from every syllable. Tonks froze. Of course he had noticed; her Patronus wasn't exactly discreet. But was it really that easy to tell? "I think you were better off with the old one. The new one looks weak."

Tonks hated Severus Snape. Her anger must have shown on her face, because Harry, standing beside Snape and still feeling his nose gingerly, looked shocked. She tried to appear calm. Severus haughtily swung his lantern round and began to stride towards the castle, and Harry made to follow him, but called hurriedly, but gratefully, over his shoulder: "Goodnight – thanks for everything."

Any time, she thought. "See you, Harry," she called back, and then they were gone and she was alone.

Why did Severus need to mock her at every opportunity? She knew he was a member of the Order whom they could ill afford to lose, and worked tirelessly for their side, but she couldn't help hating every single thing about him. Why did he have to bring up those thoughts, of her endeavours to convince Remus and his endless refusing that he was good enough, that he was a normal man like everyone else despite his… problem…

"Lumos," Tonks muttered absently. She should really be getting back to Hogsmeade, back to the bright and cheery inn and be offered free Cockroach Cluster… Tonks felt sick at the thought of going back there. It was crowded, there was no space to think, she'd have to listen to the endless shanty choruses until midnight, or until she managed to get away. She sighed. They didn't need her there for another few minutes, did they? All she wanted to do was to stop and think…

No, unfortunately they did need her. She'd been gone long enough already. She was going to Apparate right… now. Tonks began to turn on the spot.

Suddenly a whooshing sound filled her ears, making her almost fall over. She regained her balance and turned towards the source of the noise.

She frowned. Behind her was something her friend had told her about from her Muggle Studies. She vaguely remembered it was something in which Muggles used to call for help… But what was it doing here? Had it just appeared? Stranger things had most definitely happened… And what had that noise been? No Summoning Charm or otherwise made anything like that noise.

Tonks took a suspicious step forward, all thoughts of returning to Hogsmeade forgotten. She gripped her wand a little tighter, letting the light go out.

The door creaked open, and a grey-haired man with the most terrifying frown Tonks had ever seen stepped out. "What are you doing outside my TARDIS?"

"I… what?" Tonks stuttered, surprised. She was sure they were called police boxes or something, not TARDISes or whatever that man had just said… "What are you doing outside Hogwarts?" she replied.

"Did you say Hogwarts?" said the man.

"Er…" Tonks paused. How could she have let that slip her tongue? No Muggles were supposed to know anything about Hogwarts. "No," she said.

"That's Hogwarts?" exclaimed the man, pointing behind Tonks. "But that's not possible, surely?"

His exclamation took Tonks by surprise. He was talking as if he knew Hogwarts… so why was he saying it didn't exist? And what was she supposed to say? Yes, it does exist but I'm not supposed to tell you?

While she was thinking this, the man had started to stride off towards Hogwarts. "No!" she exclaimed, a little desperately. "You can't go in there- it's locked!" However, the man had already started to examine the gate. he took something out of his pocket, and Tonks heard a buzzing noise. After a few seconds, it stopped. "It is locked," said the man, sounding impressed for some reason.

Tonks had had enough. "Okay, who are you?" she called to the man, running up to him.

"I'm the Doctor," the man replied.

That sounded familiar… "Like one of those Muggle Healers, you mean?"

He turned to face her, looking surprised. "You're the real deal, aren't you?"

"What do you mean?"

"Oh!" he said suddenly. "I know who you are – you're Tonks, aren't you?"

"How do you know my name?" Tonks asked suspiciously. She knew she was quite a well-known Auror, but she couldn't help feeling like something very strange was going on.

"I know many things," replied the man- the Doctor.

"Who are you?" she said again.

"I'm a traveller," said the Doctor. "I… travel."

"How do you know my name?"

"Come on, everyone knows about the famous Nymphadora Tonks, Auror who helped Harry Potter, don't they? Or… not," he faltered, seeing her face.

"Muggles don't," she said.

"Oh, I wouldn't call myself a Muggle… actually, I would, but I'm not a Muggle in the way you'd think about it. For a start, I'm not human."

"Not… human?" repeated Tonks doubtfully.

"Oh no. I come from a planet that you won't have heard of. In fact, you probably won't have heard of any planet with life on except your own."

"You come from another planet?" Tonks said incredulously.

"Oh yes."

This was too much to believe. He expected her to be taken in with this story? "Okay, let's say you're telling the truth. So why aren't you on that… planet?"

His expression immediately became softer, and of such longing that she wondered if she should have asked that question. "It was lost," he answered. "There was a war, and the people had to be saved, but now they are lost, somewhere in this universe or maybe the next."

Just what Tonks needed. Another far-fetched explanation that barely answered her question in proper terms. She was about to say so, when she suddenly noticed his expression again. It reminded her of someone. Forlorn, hope dashed again and again, trying and trying but nothing ever changing… he reminded her of herself.

"You've lost something too," he said, matter-of-factly, but with empathy behind his words. She nodded.

"Sort of."

"You're a Metamorphmagus, aren't you?" he continued, and this time Tonks didn't bother thinking how he knew that, and nodded again. "We're more similar than you might think, you and I. We both have that something we have lost. Some things, however much you try to forget, however many times you change your face, they never go away." And then he said, very quietly, so Tonks barely heard it, "I know." He gave a sad smile, and suddenly, just like that, it was gone. "It was a pleasure meeting you, Tonks. We may meet again, but for the moment, I have travels to undertake." He stuck his hand out, and Tonks shook it.

"It was a pleasure meeting you, too," she smiled, "although I still have no idea who you are or what you're doing here."

He laughed. "You'll have to be satisfied with "a traveller"," he said, and with that, he strode back to the police box and stepped inside. The door closed with a creak, then that groaning sound started again, and the police box flashed in and out of existence and then it was gone.

Tonks laughed in amazement. What had just happened, she had no idea, but one thing was for sure, it beat free Cockroach Cluster.