The air was brisk as Amy and Sherlock stepped out onto Baker Street. Cabs were zooming past and the twilight sky was radiated over the tops of buildings. Down the street, London life was bustling, ever-ongoing. Lights from cars were zooming by, casting shadows and lighting up laughing citizens going to their favorite bars and awed tourists trying to find well-reviewed restaurants.

The pair walked slowly, side by side down the sidewalk toward their destination. They walked in contented silence, Sherlock with his hands in his pockets and Amy with her arms wrapped around herself. Amy looked up often, noticing the stars and wondering where the Doctor could be among them. She let out a low, melancholy sigh and realized that she missed spending time with him and adventuring.

"Everything alright?" Sherlock asked, looking down at a sullen Amy.

"Yeah," she replied, giving him a wistful smile. "Just missing my friend is all. It's funny how you can spend only a small chunk of time with someone but feel like they're such a large part of you."

Sherlock had felt the same way about only one other person in his life: John. He had never had a friend before, but suddenly, when John arrived on his doorstep, it seemed like Sherlock would never be able to go back to the dull, lonely life that he had before. If that was the way Amy felt about her friend, he could sympathize.

"Anyway, I'll be seeing him in only a few days, now." She looked up and gave Sherlock yet another sad smile.

"Is this your Doctor friend? The one you travel with?" Sherlock asked.

"Yeah, that's the one. Known him all my life. But he's only just come back for me."

"Come back how?"

"Well..." Amy started, looking up at Sherlock sheepishly. "No, no. You would think I was absolutely mad."

"I doubt that." Sherlock noticed Amy biting her lip indecisively.

"No. I won't tell you."

"Oh, please. Now that you've brought it up, I can't stand not knowing."

Amy looked up at him. "Fine."

"Good." Sherlock smiled at his win and then listened to Amy's incredulous story.

"When I was 7, I had an imaginary friend."

"Well, that's normal. Most children have imaginary friends," Sherlock interrupted. Amy looked up at him and glared.

"Okay, if you want me to tell you, you've got to shut your face." Sherlock nodded and Amy smiled, leaning toward him and nudging him.

"Right, so I had an imaginary friend. A man who wasn't really a man. He fell out of the sky one night with a big blue box, a time machine, he'd called it. It was small, but much bigger on the inside. And when he left, he promised me he'd take me to see the world. He promised that he'd be back in 5 minutes. But 5 minutes turned into 5 years, and then 10, and finally, 12 years and 4 psychiatrists later, he came back. But he didn't look a day older." Amy looked at her hands. "He saved me, saved the world and, without a word, he left again. 2 years later, I heard the familiar engine outside my door and when I came out to see if it was really him, he took me away. He's taken me on the most wonderful adventures. We travel time and space together and meet the most interesting, and sometimes the most frightening aliens. Up until recently, it had just been me and him, the two best friends traveling the universe together. And that's where I've been for the last 4 months of my life, and 1 day of earth life."

Sherlock was silent as Amy finished up her story. His mind was cluttered full of information, and he tried to make sense of everything she'd just said. Aliens, time travel, an un-aging man. None of it fit together. It wasn't rational. Amy had to be bluffing, waiting for him to believe and then laughing in his face. He couldn't believe it.

"Hello? Are you going to say anything?" Amy asked, looking up at Sherlock again.

"What do you expect me to say? I'm a man of reason and that, that fiction you just told me had no reason in it. You expect me to believe any of that?" Sherlock asked.

"Yeah, I expect you to believe it," Amy replied hotly. She stepped in front of him, cutting him off before he could cross the street in front of them.

Sherlock laughed spitefully in her face. "I'm sorry Amy but I think you've gone and banged your head or something, because there is no way in hell that you really have done all that you say you have."

"Really? Because I have seen things that you can't even dream of. Things that would cause you endless sleepless nights. Monsters that only live in the nightmares of children."

"Amy, there's a reason that I can't dream of the things you've seen. Because they're not real. There's no reason behind anything you've told me. The stories of children, not someone as bright as yourself."

Hot tears streaked down Amy's cheeks. "You call yourself a genius, yet you can't even accept that, somewhere out there," she pointed to the sky, "there are other worlds, infinite possibilities."

"Maybe there are, but no one, no one, has the ability to reach it. If they had, don't you think that it'd be pretty hard to keep a secret from the billions of people living here? And what of your precious Doctor? A man who wasn't really a man? So, what, you're telling me that somewhere out there are aliens who look just like us? I do think that's awfully convenient, don't you?"

"Right, so now I'm supposed to believe that everything I've come to know in my life, have spent my whole life thinking about, isn't real because you don't believe it?"

"Because it's not real, Amy. It can't be. You have to think."

"I am thinking. And I'm the only one thinking right. Don't believe me. I can't tell you what to think, but I'm telling you what I know."

"What you know is wrong." Sherlock spit the words at her and then turned to cross the street, leaving her, tear-stained and stricken by his outburst.

Sherlock stepped out a few feet onto the street and, as though she were watching the scene from outside of her body, Amy heard the squeal of tires and bright light illuminate the man who suddenly seemed too far away from her. Sherlock seemed unable to move, nailed to the spot, and, somewhere distantly in Amy's mind, the term "deer in headlights" came to mind.

The truck barreled forward, hurtling toward an unmoving Sherlock.

"Sherlock! No!" Amy screamed, reaching out, as if she could pull him back to her. She knew she had to do something. Almost in slow motion, she ran forward and sprinted toward him, slamming her body into his. They seemed to fly through the air until crashing to the ground. Sherlock felt the air leave his lungs, forced out by the sudden impact. Somewhere very close behind them, Amy heard the truck's horn blare but she felt no impact. It traveled down the street and eventually out of sight. Quickly, it was all over. Amy looked at Sherlock, who she had landed on top of, and saw a look of utter astonishment pass over his face. It was the last thing she saw before everything went black.