One thing I knew was for certain: everything in my life had become a memory, and I knew the Doctor would be just that. He was the one thing I wanted to hold onto, keep safe inside and beside me, but I couldn't. Our whole relationship, both platonic and romantic was slipping through my fingers. And it had always been in the back of my mind that there was no way we could ever be what I wished for us. If it had of been up to me, I'd have married him, had his children and kept on travelling through time and space. But, that wasn't an option. The Doctor was a loner by nature, despite having companions to look after him, none of them ever stayed. They all moved on in the end, moving into their own lives.

I had to be the same. I couldn't be different.

I began to think back on when I'd met him for the first time. He'd been investigating strange happenings in the house two doors down. I couldn't help but be nosey as he stood outside the front door, waving his sonic screwdriver in the air. The first time I'd seen him do it, I'd laughed. My instant thought was, "Oh, no. Call the men in white coats." Then I'd noticed the TARDIS standing quite comfortably on the car park directly opposite. No one else had seemed to pay any attention to the old style Police Box standing in plain sight and so out of place. My inquisitive nature at this point had taken hold and I made my way out of my flat and down to the house which was still unoccupied.

Suddenly I came back to reality and looked down at the packed bag beside me on the bed. I knew this was for the best. I needed to leave, for my own sanity. If I didn't leave then I'd become more accustomed to this lifestyle and pine away when it all disappeared. It was obvious that I needed to leave now; not in a year, not in ten.

My hand drifted down the pillow and I remembered the pillow fight we'd had the week earlier just after my illness had gone. I'd never laughed so hard in all my life, apart from maybe the day when my dad fell in a pot hole. We'd been walking my dog in the countryside after taking a day trip out with a picnic. My mom was sitting in the sun, soaking the rays while I'd ventured off with Dad. Suddenly he shouted out loudly and when I looked down, he was scrambling to get out of a hole which had been hidden under the foliage.

He glared at me angrily. "Help me, then!"

I stood there laughing hard for a minute or two before finally lending a hand to help him out.

During my time with the Doctor, I'd seen so many beautiful sights, met some of history's most famous figures and ran away from frightening enemies. I'd seen the Titanic set sail from Southampton, met Elvis Presley, seen the death of Tutankhamen ...the list was endless. And all of this was now only a memory, perfectly preserved in my head. And tomorrow the Doctor would be just the same.

A lump caught in my throat as I heard his voice echo down the hallway.

"Sarah? Sarah? You must see –"

Then he looked down and saw my bag and looked at my red, sore eyes.

"W...when did you decide this?" he asked, standing in front of me.

I swallowed sharply. "Last night. Doctor, I can't stay here anymore. The things that have gone on between us and you're expecting me to act like they never did? I can't. I can't stay here, knowing I love you, and we can never be anything more than this. Please don't expect me to. It might be easy for you –"

He cut me off. "It's not easy for me. Why does everyone think it's easy for me?"

I couldn't help but break down into tears, and as I did, he moved the bag off the bed and sat beside me. However, he didn't comfort me. He just carried on speaking. "Sarah, I was selfish to ask you to come with me. So many see this life and then have to go back to living their own, and maybe by me doing this time and time again, it's just..."

I looked up at him and saw that tears had also formed in his eyes.

"I need to make the decision," I said softly, trying to be strong for him now. "You came back for me before when I needed you, but ultimately, in the end, I have to decide to walk away. I have to be strong and recognise that what's happened just can't be. I had nothing and you gave me everything."

The Doctor smiled through the tears. "If you ever need anything...I'll come," he told me. "Make a wish."

"Do you tell everybody that?" I asked, remembering his fond words spoken for Madge Arwell. She'd been the woman who thought she was widowed and saved her husband from crashing his aeroplane during World War II.

"Just the special ones," he replied. This time he drew me in and put his arm around me. I looked up at him and smiled, then felt him kiss the top of my head. He truly had brought me from nothing to give me everything. My life before the Doctor had been quite bleak, mundane and mediocre. Nothing special ever happened, until I met him. I was always under the assumption that aliens didn't exist, but as more news reports of alien crash landings and attempted Earth annihilations came in, I wasn't quite so sceptical. And the Doctor had been the helping hand behind each one. Two years in a row he'd saved the Earth, once in a leather jacket and once in a striped suit and Converse. How many other times had he saved us and we hadn't noticed?

I remembered in detail the very day that my neighbours had gone onto the rooftops, Christmas Day morning, walking up in a trance to the highest place they could get. Thankfully, I hadn't been one of the ones affected. I'd only been seventeen at the time and absolutely terrified. My mom was hooked to the TV and Dad was out in the street with other people, wondering what was happening.

The year before that and a spaceship had crashed into Big Ben down in London. Being on the outskirts of Birmingham meant that we saw very little of these things happening. They always seemed to affect the capital more so. Well, the large scale dangers did anyway.

I'd always believed in God, however, not really attaching myself to a particular faith. But I felt that we were all governed by a higher power and the Doctor was somehow a blessing from that power. An angel of sorts. He was an angel to each and every one of us, but especially to me. He'd lifted me when I needed him, but it was now my time walk away and rely on my own strength.

"Will you be okay?" I asked him, holding my head on his shoulder.

"Aren't I always?" he asked.

I just looked up at him, keeping a straight face. "Well, you say that."

"I say lots of things, Sarah." He then looked down and started to laugh. "You're not in a huge rush, are you? Maybe one more day? I can drop you back home in the morning."

"One," I insisted.

"We can do whatever you wish...got wherever you like," he said.

"I'd like to just stay here with you," I replied, looking into his eyes. "We rush around a lot, and it'd be nice to just stay here. I can cook some fish fingers and get the custard out."

He grinned. "Ohhh..." Then he rubbed his hands together. "You know the way to my hearts."

"We could have a swim, maybe pop in the library and then have an early night with some DVDs."

"Like a proper sleep over. Do each other's hair?"

I couldn't help but laugh at him. "Put your bow tie in your hair. That'd be a good look on you."

The morning began with a swimming competition in which the Doctor won. I'd never been a particularly strong swimmer and got tired half way through. He put his hands high into the air with a triumphant shout, marking his victory. "I let you win!" I called over, teasingly.

With a big grin, he jumped into the air and then dived back under the water. I watched as his dark mass, which loomed under the water, came nearer to me.

"No!" I called out, laughing. Only to be then pulled under playfully. He grabbed me, pulling me down to the bottom and then gradually we lifted back up to the surface.

I looked at him as he smiled like a boy, forgetting for that second that he was many centuries old. His attitude sometimes would give you the impression that he indeed was a man in his late twenties, early thirties who loved to play jokes and be jovial. But then the look in his eyes told otherwise. The fog of painful memories would descend and his brow would crumple, finally showing something closer to his true age. The look in his eyes was like the one my granddad would give me when remembering my grandmother; pain, sadness and sometimes a tad of regret.

We dried ourselves off after another swim and then made our way into the kitchen area. I grabbed a box of fish fingers and a carton of custard.

I looked up to see the smile dance across his face. "Aren't you having anything?" he asked.

"I might put some fruit in the custard," I replied. I didn't eat fish and the whole combination idea made me feel sick.

Once the fish fingers had been cooked to golden, I placed them on a plate next to the bowl of fresh custard. Then I chopped up some fruit and put it into my own bowl of custard. And together we ate, sitting comfortably opposite one another. He'd look up at me now and again, a small moustache of custard forming on his top lip which he'd wipe away at regular intervals.

After lunch we sat in the library, choosing a book each and then let our meals go down. The Doctor opted for a classic by Charles Dickens, whom he'd apparently met. I decided to try The Man in the Iron Mask by Alexandre Dumas. I'd tried it once a few years after the most recent version of the film was released but couldn't get my head around it.

I'd see him every now and again looking up at me over the top of his circular spectacles. Then as I looked at him, he'd begin reading again.

"Good book?" I asked.

"Well, if I'd have been him, I'd have written it a lot different to this. I'm a huge fan and everything but I wouldn't have made the characters act the way he does," the Doctor explained.

"It's a book, Doctor."

"It's not just a book, Sarah. It's a piece of history, a snippet of the time in which Charles lived. These books have lived on for years after he died."

"Alright...sorry," I said, dropping my gaze back down to my own book. "Didn't realise you got so attached to books."

He sighed and pulled off his glasses. "Why is it so bad to get attached to things?"

I felt that there was more to this than just some bloody Dickens book. There was something he wasn't telling me, and I had a feeling I already knew what it was. However, I didn't want to develop a sense of importance.

I knew I'd hit a nerve and watched him walk away without another word spoken between us. I'd go after him in a few minutes, but first I knew it was best to let him calm down.

I tried my best to remain away from the Doctor, to give him some space to think. But I knew what was upsetting him; deep in my gut I knew what it was, and a few minutes later he'd confirm it to me.

The console room was quiet and as I walked in, still awestruck by the beauty of the mechanics, I saw him. He was leaning over the main console in the centre, the palms of his hands resting against the metal.

"Doctor? I'm sorry what I said about the book and everything..."

"Sarah, it wasn't about the book," he replied softly.

I approached him and could see the tears swimming in his eyes. He never looked at me so I walked around the console and moved in behind him. I tried hard to breathe over the lump in my throat. And gently, as I stood directly behind him, I reached out and touched his hands which were palm down on the edge of the mechanism.

"Sarah...don't," he whispered. "I can't..."

"Doctor, just tell me."

He turned and as he looked down at me, tears were falling in a quiet procession down his cheeks. "You said you needed me and I came back for you. But now..."

"You need me?" I asked.

He never answered, but I could see in his eyes that what I'd stated was spot on. He now needed me; maybe he'd always needed me, but my need had temporarily surpassed his. In that moment I was torn, torn between his need for me and my need to be strong. Didn't love involve sacrifice? It'd mean sacrificing my own future and the strength I felt I was finally finding in order to meet the need he had. I knew full well that he'd never gotten over Amy and Rory. They'd always hold a very special place in his hearts. As he'd often say, "Amy was the first face this face saw."

"I'll stay with you as long as you need me, but we can't carry on like this forever," I told him. "If we stay together too long, it's going to hurt more when we do have to part ways."

"Do you think I'm selfish?" he asked.

I put my arms tightly around him, kissing his cheek as I did so. For a couple of seconds, I tightened my grip on him, feeling him reciprocate. "You're the least selfish person I've ever known."

After our heart to heart, we decided to have a film night anyway. I no longer planned on leaving the TARDIS. But I knew I couldn't make this too long term, no matter how much the Doctor needed me. I was in love with him, far beyond any love I'd ever felt before, and I needed some kind of sanity. I knew where I stood and with the Doctor, as I'd often thought and had been stated, no kind of romantic relationship could be upheld. He was off limits to being the husband and father type in the way I understood that. True he was married to River, but their relationship baffled me. It was unlike any kind of marriage I'd ever encountered.

I watched as the Doctor cried through Dumbo and laughed at Liar Liar. Somehow I couldn't quite get into the films; I kept letting my mind wonder. One day when I left the TARDIS, he'd just be a memory. I'd have no everlasting part of him. But for now I had to put all that away, file it at the very back of my mind for later contemplation.

For now I'd be what he needed: a companion.