She hadn't really thought about what she was expecting the Christmas Planet to be like, but Evie couldn't deny that it suited its name perfectly. Considering the Doctor's track record, anything would have been possible, but the eighteen-year-old had stepped out of the little blue Police box and been confronted by snow as far as the eye could see.

There were even Christmas trees, decorated with tinsel and baubles and tiny, shimmering lights. Evie automatically went towards the nearest tree, her hand stretched out eagerly to touch it. The Doctor grabbed her by the shoulder, pulling her backwards and aiming the sonic at the plant. He looked at the readings before grudgingly nodding towards the teenager.

"What was that about?" Evie asked, rolling her eyes. "It's just a tree."

"Not everything is exactly what it seems. I've had a run-in with killer Christmas trees before…" He said slowly. Evie shook her head; everything with this man was just one big drama.

"Well this one is just a tree, yes?" She waited for the Time Lord to nod, before she continued. "Doctor… this is the Christmas Planet. What could possibly go wrong?"

He raised his eyebrows but said nothing. The teenager pulled a face, realising what she'd just said and instantly regretting it. Anything could go wrong; everything in fact. But right now it was Christmas Eve and she was on the Christmas Planet. It was too exciting to worry about killer Christmas trees or… psychopathic Santas. As she told the Doctor her philosophy, he raised his eyebrows and whistled.

"Let's just hope we don't run into any of those."

There was so much that Evie didn't know and she got annoyed when the Doctor said something cryptic like that without any sort of explanation. But she was getting better at knowing when to demand information and when not to. Right now the Doctor was wearing his I-don't-want-to-talk-about-it face, so the teenager kept her mouth buttoned. Instead she focused on what was around them.

After a couple of minutes, however, she got bored of taking in the merits of snow and decided to badger the Doctor for information instead. Not about the Santa comment, she guessed that he really didn't want to talk about that. Instead she decided to ask him about other worlds and the things that lived on them.

"So… Doc." Evie said with a sly smirk; she knew he hated it when she abbreviated his name. At least it would bring him out of his thoughtful mood. "Where else have you been… I mean, you've told me some things, but you're like… really old. There must be so much else that you've seen and done."

The Doctor smiled, indulging her as she spoke. "There are lots of things." He agreed.

"So… tell me. I want to know."

"Name something, somewhere?" He told her with a grin. Evie thought for a moment; her ability to follow that request was limited; the only places and things that she knew where the ones that she'd seen or heard about.

"The war?"

"Which one?"

"First."

"I was there… muddy…" He shuddered slightly, a shadow passing through his eyes. Then he smiled. "Think harder, Evie. That was an obvious one."

Evie looked puzzled, but then thought harder. "Pompeii?"

"Ahh!" The Doctor laughed. "Pompeii… I was there right at the end." His expression changed, suddenly sad. "Me and Donna… It was my fault."

"Your fault? It was a volcano. You can't cause a… oh…"

He was looking at her with so much guilt in his eyes that she couldn't bring herself to carry on with her sentence. Normal people couldn't cause a Volcano, but this was the Doctor they were talking about – there was no one less normal. For a couple of minutes they continued in silence. Then the teenager's curiosity got the better of her.

"I'm sorry, Sweetie… but… what happened? Was it an accident?"

"No. I… I had no choice. It was Pompeii or the Earth."

Evie chewed her lip nodding slowly. She'd known there had to be a reason. He looked so sad still that the girl slipped her hand into his, squeezing it tightly. The Doctor glanced at her, a weak smile on his lips. Then, after closing his eyes for a moment or two, he smiled more broadly.

"Try another one."

"Really?" Evie couldn't believe that he actually wanted to carry on this conversation. She didn't want to bring back anymore bad memories for her friend.

But even the most innocent things might do that. What if she said something totally innocent… like the Queen's coronation, or the day she had been born… and it turned out that it held bad memories for him? Evie couldn't bring herself to cause him any more pain. Especially not straight away.

Then she had a thought. "Doctor… tell me about Donna."

"I have." He said, furrowing his eyebrows at her.

"No, you've mentioned her as part of your great adventure stories." Evie argued, raising her eyebrows. "I want to know about Donna… Donna Noble?"

He sighed, smiling. "Donna Noble… where do I start with Donna Noble." The teenager grinned and sat down on a tree stump. The Doctor looked at her, a mixture of amusement and confusion on his face. Then he sighed, brushed the snow off a tree stump just to her left and sat down.

"Right… story time."

"Donna… she was… she was so beautifully human. And persistent. Donna was nothing if not persistent. I met her first at her wedding –"

"Her wedding?" Evie cut in, unable to stop herself. "You ruined her wedding, didn't you?"

"Who's telling this story?" The Doctor asked, raising his eyebrows. Evie pursed her lips, signalling that she'd keep quiet. The man doubted that would last very long. "Anyway… there was a Racnoss – like a big spider woman – and her husband, fiancé, whatever… was working for it. So, after we sorted that out I… I asked her to come with me. But she said no."

"She said no? Was she crazy?" The Doctor smiled at her outburst, knowing that she wouldn't have been able to keep quiet for long.

"Yes." He said simply. "But she was also amazing. She found me… I found her… whatever. We found each other a while later –"

"– after Martha?"

"After Martha." He confirmed. "So then we travelled together. It was brilliant. She was brilliant. She figured out there was something odd going on with the Adipose Industries and –"

"Adipose Industries… like the Adipose that we saw?" Evie cut in again. The Doctor sighed and shot her an exasperated look, but nodded.

"Yes. Anyway… then there was so much more. ATMOS, Agatha Christie, the Ood, The Library… Donna was with me when…" He paused for a split second, something flitting through his eyes. "And when Jenny… But Donna, she was so human. She reminded me how to be human – properly human. And she was brave and feisty and fun. You'd have loved her... she'd have loved you. She used to tell me how much she hated me as well and she used to hit me if I annoyed her; you're very similar. Donna was my best friend." He smiled sadly. "On second thoughts, it's a good thing you can't meet her. I don't think I could cope with the pair of you at the same time."

"I can't meet her?" The teenager asked, bewildered. "Why? She's not… dead?"

"No. There was… basically in simple terms she had absorbed Time Lord Knowledge and it was dangerous. I was forced to wipe her memory. If she remembers me, even for a second, it'll cause her brain to burn out."

"You have a good effect on women, don't you?" Evie said sarcastically. But she looked worried.

"That won't happen to you, don't worry." He reassured her. "I promise."

Evie wasn't convinced, but she trusted him; she couldn't help it. Then her curiosity kicked in. "Who's Jenny?"

"Jenny… my daughter."

The teenager's mouth dropped open. Something raged through her… something that felt suspiciously like jealousy. "You have a daughter?"

"Had… yes, technically. She came from my DNA. Donna named her. But she's dead." He said, shivering slightly. "Come on, let's keep going.