A/N: To celebrate reaching 500 followers on tumblr recently I took a load of prompts as a thank you. This one was from elizasurpriza:

"Congrats on 500! I'll take Rose and the Doctor discussing HP, or the golden trio discussing Doctor Who, please."

I went with the former. Harry has enough misery in his life without adding Doomsday to it. This story contains huge spoilers for all HP books just in case you are one of the three people who haven't read or seen them.

Disclaimer: I am not the BBC, RTD, JKR or anybody with famous initials.

It was on an average Saturday that Rose felt she had let the New New Doctor down for the first time. They were on a planet she had no hopes of pronouncing the name of, surrounded by the three legged guards of the prince that he had just offended.

Okay, so maybe not so average.

"You will apologise to the Prince!" yelled the guard at the front. Despite being a full two feet shorter than the Doctor, Rose thought they were still intimidating, what with their cattle prod-like spears.

The Doctor snorted. Apparently a couple of centuries of being constantly threatened helped build up an immunity.

"You attacked him and you will apologise! Immediately!"

"Oh, come one!" the Doctor laughed. "His cape-y, robe thing caught fire. I was putting it out! I was helping!" He stood straighter and nodded. "I should be rewarded."

"Don't push it," hissed Rose when the guards made angry gurgling noises at them.

"I don't know what you're talking about," the prince replied, water dripping from his beard. He spoke so sincerely that Rose would have believed him had his cape-y robe thing as the Doctor so eloquently described it, not still been smoking slightly.

"That is a Cornelius Fudge level of denial!" crowed the Doctor. He glanced over at her and frowned.

"What?"

"You didn't laugh at my joke," he pouted.

"Ha."

"It was funnier than that!"

"Right, well, I'll laugh at it when the prince stops glaring at us like that." Rose shot a pointed look at the prince in question and wondered if this was part of his plan.

It probably wasn't, judging by how genuinely hurt he was. "You normally laugh at my jokes."

"Stop talking to the woman and apologise!" growled one of the guards, but the Doctor was apparently completely bored with the whole might-be-getting-arrested conversation.

"Cornelius Fudge?" he explained. "Minister of Magic?"

"What planet was that again?"

"What - what planet? Yours!" the Doctor squeaked. "He's in Harry Potter."

Rose shrugged. "Never seen them."

The look he gave her, she might as well have just informed him she wished to marry a Dalek and, though she knew they had a bit of history, could he put it behind him just for one day so he could give her away?

"Rose Tyler, what are you telling me?" he asked in a dangerously low voice. "How can you - wait - did you say seen?"

Meanwhile, the prince's guards seemed to care less about Harry Potter than Rose did. "You will cease-"

The Doctor whirled around and scowled at the guard. "Can't you see I'm having a serious conversation?" The guard blinked as though no one had defied him so blatantly before. "Thank you. Now, Rose," he continued as there had been no interruption, "you're saying you've never read a Harry Potter book?"

Rose shook her head while the guard raged behind the Doctor.

"Let me solve this little misunderstanding, we'll go back to the TARDIS and I will fix that," the Doctor said. Over his shoulder, Rose saw the guard raise his spear, a green energy bolt glowing at the tip, and knew it would likely be at least a few hours until she'd be going to be anywhere near a copy of Philosopher's Stone.

As it was, it only took a couple of minutes for the Doctor to recover from his shock and for one of the guards to admit that he had accidentally set his prince on fire. With a formal apology and a couple of cape-y robes things of their own, the pair of them were back in the TARDIS before sundown.

The Doctor threw his new garment over the railing, followed by his coat, and bounced up the ramp. By the time Rose had joined him, they were in the vortex.

"Dinner?" suggested Rose. They hadn't had chance to eat, having spent most of their time on the planet avoiding a diplomatic incident.

"Nope. Library." The Doctor clapped his hands onto Rose's shoulders and started pushing her down the corridor.

"Is this about the Harry Potter thing?" Rose whinged. "Can't we eat first?"

"You've already been denied the joy of Harry's world for far too long," the Doctor told her seriously. "How, I don't want to think about, but it ends here."

Rose blew her hair out of her face and made a point of leaning back and trying to plant her feet on the grated floor.

"If you think that will save you, then think again," the Doctor warned. "Chapter One. The Boy Who Lived. Mr and Mrs Dursley, of number four-"

"Hang on - have you got the whole thing memorised?"

"Only the first four."

"Chapters?"

"Books."

Rose sighed and allowed herself to be transported to the library, knowing she would be fighting a losing battle if she were stupid enough to start one. She'd seen him get passionate about a lot of things. Justice. The Jam. Jam. This was something else, however. Normally he'd happily talk her ear off, flailing his arms around because words alone could not possibly convey just how world shatteringly important it was that this thing existed. If she listened, he carried on and would venture off into anecdotes and related subjects. If she didn't, he moved onto the next thing. This was the first time he was pushing her - physically pushing her - to join in.

Three hours later, Rose knew why.

Three hours later, Rose wished she could cross her own time stream in order to help him push herself towards the library.

After that it was hard to tear her away from the book. The Doctor couldn't have been happier. If anything, the look on his face when she asked if she could take it with her to read it before bed was the best part of the whole experience. The whole of time and space at the end of her eager fingertips and Rose was spending all of her time curled up with the Doctor and these children's books she'd never cared about before, having the time of her life.

Though he refused to spoil anything for her, the Doctor was more than happy to bounce theories off and even found a twenty-fourth century Sorting Hat for her to try on. He celebrated every Quidditch win with her, held her as she cried over Sirius and even saved Half-Blood Prince from being thrown at a wall when Snape killed Dumbledore.

With the tears from the resulting funeral still drying on her face, she'd asked him if he could get the next book while she made them some sorely needed tea.

"It's 2006," he replied, a crease forming between his brows. "For you, anyway."

"So?" Rose croaked.

"Deathly Hallows doesn't come out until 2007."

She stared at him. "We're in a time machine."

"I'd noticed."

"So just… jump ahead."

"What? And spoil the thrill of the wait?" He jumped up so he was crouched on the sofa facing her, his eyes alive with excitement. "That was the most exciting time of the entire series, Rose! The theories, the discussions, the arguments! Would Harry survive? Whose side was Snape on? Why was Florean Fortescue kidnapped? Would Ron and Hermione finally get together? Was Umbridge the main antagonist all along? No one knew and we all had to wait, Rose!

"For those few months, people of all ages, all nationalities, all religions, genders and - and star sign were united. Midnight came, records were broken and one of the greatest stories ever told came to an end."

"How long did you wait?"

"About three minutes," he replied. "But I went back after I'd finished it and queued up at midnight."

No matter how much Rose protested, the Doctor refused point blank to let her near a copy of Deathly Hallows. She'd tried every corner of the TARDIS but it seemed the ship herself was conspiring against her as well. Any time they visited Earth in her future, the Doctor kept her away from bookshops and libraries. He even caught her asking Chloe Webber if she had a copy.

Then, as luck would have it, she was browsing a market stall on the other side of the Milky Way when she saw a battered purple and red book she had been hunting for for months. Nearly taking out one of the other shoppers, she pounced on it before the Doctor could stop her.

"Chapter One," she read. "The Dark Lord Ascending. The two men appeared out of nowhere-"

"What are you doing?" the Doctor gasped, appearing out of nowhere.

"Oh, please," begged Rose. "I've started it now!"

"No chance. Hand the book over."

Locked in a staring contest, Rose did her best to flirt without breaking eye contact or being too obvious.

"Rose…"

Damn.

Desperate times called for desperate measures and Rose was more desperate than she'd like to admit to start looking for those bloody horcruxes.

"If you don't let me buy it," she said deliberately so he wouldn't miss a word, "I will read the last page."

The Doctor's eyes went wide. "You wouldn't."

Rose flipped the book over, a picture of Hogwarts castle now visible with the blurb.

"Don't."

She opened the back cover, still watching him sweat.

"Fine," he relented. He jumped forward to slam the book shut before she saw any of the words. "But you read all of it with me."

"Why?"

"It's the best one and I don't want to miss any of the good bits," he grinned in response. He took the book from her to grasp her hand and pull her towards him. "Anything else you need before we go?"

"Um… Oh, yeah! I saw something I wanted to give my mum." She moved from where she had buried herself in his coat and picked up a small trinket from the table next to her. "Thought she'd like this. 'S'sort of pretty, don't you think?"

"Oh yes," he replied softly, not looking at the object in her hand. "But it's not just for decoration, oh no. Bazoolium's got a few uses…"