A/N:This short story will be a TMNT/Supernatural crossover. I wanted to read one, but I couldn't really find many. So, I decided to write my own! Sorry, Michelangelo-centric again! I love the little guy.

Prologue.

Excerpt from the diary of Hamato Yoshi, 23日, 9月.

In three days' time, we shall be experiencing a rather significant event in our home.It has been almost two years since my sons and I were exposed to the mysterious substance that forever altered our bodies, and our lives. I have taken to calling this anniversary 'Mutation Day' in order to create a little celebration for my children (as I am naturally unaware of the precise date of their birth). The boys seem rather taken with the idea, particularly Michelangelo, who has requested "cake, Daddy, cake!" I do not know from where he has obtained the knowledge that special events are to be accompanied by cake (though I suspect the television may be to blame), but the other boys were soon whipped in to a frenzy as well. How am I to procure cake from the materials provided by a sewer?

Excerpt from the diary of Hamato Yoshi, 24日, 9月.

I believe I have 'bitten off more than I can chew', as the expression goes. My sons remain overexcited, and ask me near constantly when the party will commence. Today, I have taken them to a place that has often soothed their rambunctiousness in the past.

I happened upon the tunnel close to the time that we were newly mutated. Still reeling from my sudden dash into the sanctuary of the sewers, I had taken my new children for a walk to calm our nerves. With the infants squalling and my patience fraying, I almost didn't notice the patch of sunlight that I had stumbled into. A damaged grate above my head looked onto a lonely, thickly wooded area that I could only assume belonged to Central Park. Some vegetation, sustained by the damp atmosphere, had even made its home in the tunnel itself, creeping along the concrete walls, and softening the ground. The whole area smelt a little odd, particularly with my newly heightened senses, but that was not so unusual in a sewer. There was a dilapidated sign on the wall that read '49'.

I digress. My sons are now old enough to play on their own in Tunnel 49 as I sit under the damaged grate. I like to feel the sun. It is a luxury that I may no longer indulge in as I please, and such times are precious to me. I could hear the boys laughing together and chattering in a mixture of the Japanese I have been teaching them as their first language, and a few words of English gained from the television. The sound was soothing, my children were happy. A comfortable heaviness sunk into my limbs as I drifted into a doze.

I was awoken some time later by a heavy 'thump' upon my lap. Blinking down at the miscreant, I identified a sleepy Raphael attempting to burrow into my yukata. Leonardo and Donatello were curled up at my sides, fast asleep. The light emitting from the grate had changed to the sorrowful gold of an early autumn sunset, and the temperature was dropping fast. Gathering my sleepily protesting children into my arms (thankfully, they are still small enough that I may do so), I called softly for Michelangelo. My youngest is apt to wander if given the inattention with which to do so, though he never goes far, preferring the comfort and safety of his older brothers. However, this time, I was alarmed to find that no sound of tiny toddling feet answered my call.

"Raphael," I addressed the son that wasn't currently missing or napping in my arms. "Where is Michelangelo?"

He blinked up at me, green eyes unconcerned. "Mikey sit ova' dere," he said, pointing to a branch splitting the tunnel in two. The sunlight had receded from the smaller tunnel, creating clinging shadows and a deep sense of abandonment. My ears flattened instinctively against my head, but I dismissed the foreboding feeling as that of a paranoid father.

"MIKEEEEEY!" Raphael's call startled me. Perhaps he sensed the sudden urgency that the side tunnel evoked in me. "Come out now!"

Shushing my son before he woke his brothers, I descended further into the tunnel. The three in my arms shivered a little as the air became noticeably cooler away from the dying sunlight, but I could hear a faint little voice in the distance. I broke into a run, the jogging movement waking Donatello and Leonardo, who began to whimper.

"Sorry, little ones, I am sorry—MICHELANGELO!"

The sight of my youngest filled me with such great joy, I did not even question his cross-legged seat in front of the curved, brick wall of the tunnel. He was chattering away intently, and seemed unaware of my calls.

"What you name? Dat p'etty…I Mikey! I p'etty too? Why you in dere?"

It seemed as though he was having a conversation with somebody. The content made me smile a little; 'pretty' was Michelangelo's word of choice these past few weeks. I knelt next to my youngest son, shushing the older three who were whimpering against my clothes.

"Who are you talking to, Michelangelo?"

He jumped in surprise and turned to face me, breaking into a smile. "Daddy, da lady in da wall!" He said this with no small amount of admonishment.

"There is no lady in the wall, my son. Come, let Daddy take you home." I reached out to take him into my arms, and the tiniest flinch from his small frame startled me. He seemed to shake it off, and took my hand quite willingly. I hissed with shock.

"My son, you are frozen! Here," I scooped him up and popped him inside my yukata, against the fur of my chest. I had to get my little ones back home.

Excerpt from the diary of Hamato Yoshi, 25日, 9月.

I have thought of a good plan. Since algae and worms (the boys' staple diet) are plentiful in the sewers, I shall attempt to mould them into the shape of a traditional birthday cake. I know that I have many small taper candles in stock (the electricity in our home cannot be trusted, and is liable to go off at will), so I will put one on top.

I must admit, even I am affected by the festive atmosphere surrounding my sons! Later, when I have put them to bed, I will string the paper chains that I have made about the kitchen.

I hear my sons' overexcited squealing from the living room. I think it is time for lunch.

….

I fear that Michelangelo has caught a slight chill from sitting in the cold tunnel for so long. The poor boy was quite uninterested in the lunch I set before him; he merely turned up his nose and demanded to be held. I made a compromise with him; I would hold him in my lap if he let me spoon-feed him a little algae. Even with my help, he ate very little, and seemed more interested in getting closer to my fur by cuddling into my clothes. I gave the remainder of his meal to Raphael.

After lunch, I settled the boys in together for their afternoon nap. Thankfully they still fit in the same little bed. Soon, I will have to see about making three more.

Michelangelo seemed content to cuddle with Donatello in place of me, but the poor thing was shivering, and sniffling plaintively. I plucked him from the cot and placed him in between Donatello and Leonardo, whereupon he immediately tried to snuggle as close as he could. Donatello looked at me, eyes shining with as much solemnity as a two-year old could muster, and announced, "Daddy, Mikey vewy cold!"

"Yes, Donatello, he is not feeling well. Perhaps you might give him a cuddle to warm him up?"

"Mikey sick?" Leonardo had taken notice, his beak scrunched up with concern. I was gratified to notice that he and Donatello crowded close to their smallest brother to share their warmth, and was privately amused when Raphael clamped onto Leonardo's shell, determined not to be left out.

"Sleep well, my sons."

….

It would appear that my concern for Michelangelo was unfounded. He seemed perfectly fine after his nap, pestering me for food (an easy request to grant, since he missed lunch), and asking whether we might go to our "p'etty tun-nel!" I had to say no; I fear that, however well he seemed, it would not be good for him to play in the dampness of the sewer.

For a moment, his face clouded over, and I warily anticipated a tantrum. Michelangelo is a sweet, loving child, and far less prone to fits of temper than his older brothers, but there have been times in which he has clamped on to an idea, and not let go. Thankfully, this time he agreed quite happily, and toddled off to play with his brothers. I watched as he dived onto Leonardo's lap for a cuddle, and went to prepare dinner.

Excerpt from the diary of Hamato Yoshi, 26日, 9月.

This morning, I awoke early to prepare the requested 'cake' for our Mutation Day. It was not as difficult as I had previously anticipated; however, the algae mixture would require time to 'set' in the refrigerator. Hanging the paper chains was also easy with no little turtles under my feet, so I found that I had time to sit and contemplate the journey we have all undertaken since that fateful day three years ago. The reminiscence is bittersweet; my memories of that time call up the figure of the broken man that I was, still reeling from the loss of my beloved Tang Shen, and beautiful Miwa. However, when I walked into the pet store looking for a low-maintenance companion, I could never have dreamed that the four little turtles I couldn't bear to separate would become my new family. I am oddly grateful to those strange men for giving me a reason to smile again.

…..

The Mutation Day celebrations started smoothly. My sons were ecstatic to wake up to the festivities that I had prepared. Donatello demanded to be shown how to make paper chains, and now our home is utterly festooned with the colourful decorations! For a rare treat, I took them into the dojo (because of the possibility of injury from my collection of weapons, little turtles are strictly forbidden from entering) and put some music on my old, battered record player. Michelangelo showed quite the aptitude for dancing, but eventually grew tired and tripped over Raphael, who was lying on his front inspecting the tatami mats. Needless to say, Raphael did not appreciate this, so I swiftly distracted them from the inevitable scrap by announcing that it was time for cake.

Oh, how enchanted my sons were by my (somewhat feeble) algae-cake! I lit the thin taper candle and turned down the lights; how their eyes shone! It did me the world of good to see them tucking into their food so enthusiastically. I must remember this for the future. This day is a complete success.

….

I fear all is not as well as I had hoped. My sons and I were exhausted by the unusual activities of the day, so I put them to bed a little earlier than normal, and soon retired myself. However, I was awoken an hour later by the sound of wailing coming from my sons' room. After rushing to their sides, I was greeted by the terrible sight and sound of Michelangelo vomiting in his sleep. His elder brothers were crowded at the other end of the cot, scared out of their wits.

"Stoppit, Mikey!"

"Daddy, Mikey sick!"

"Hewp, Daddy!"

I wasted no time in scooping the ill child into my arms, lest he choke on his own vomit. I shuddered at the feel of his deathly-cold skin; something definitely was not right. Before I knew what I was doing, I had reached the bathroom, and begun to fill the tub with warm water. Throwing my robe to the damp floor, I climbed in with the bundle in my arms, holding him tightly against my chest in an attempt to warm him up.

"Michelangelo…my son, please wake up…"

He was not vomiting anymore, but neither my warmth nor that of the water surrounding us was succeeding in making his icy skin any warmer. Hearing a noise at the bathroom door, I looked up to see my three eldest boys, shaken and huddled together. They seemed reluctant to enter.

"It is alright, children. You may come in."

The three of them shuffled tentatively towards me. Donatello reached out a pudgy green hand and stroked his little brother lightly on the head.

"Mikey ok?" he asked me. "Daddy make Mikey better?"

Leonardo and Raphael looked hopefully at me, displaying the trust that their father could make everything alright again. I looked down at the shivering baby in my arms, and was gratified to see that his eyes were open a fraction.

"He will be fine, boys. I think he just has a small cold from sitting in the tunnels for too long. Come," I stood, and wrapped us both in a soft towel. "We will all sleep in Father's bed tonight."

They agreed enthusiastically, and we settled ourselves in my futon, all four children curled up together on my chest and belly. It made for an uncomfortable night, given the fact that whenever my frightened mind relaxed enough to fall into a light doze, I experienced a chubby hand tugging my whiskers, or a hard shell to the stomach. However, it was better that I stayed awake to watch over them. Whatever Michelangelo had, his brothers stood a good chance of catching it, so I monitored them all closely.

Michelangelo himself had a fitful night. He shivered near constantly, despite laying on my chest with his brothers and blankets arranged carefully on top of him. He never woke, but he murmured sometimes. It was difficult to pick up on whatever he was saying, but one word stood out clearly.

"Mama," he whimpered. "Ma…ma, Mama…"

I was honestly confused, and more than a little unnerved. None of the boys had ever brought up the …..subject of a mother before. I had not even told my little ones about Tang Shen, as I feared their young minds would not be able to comprehend the concept that there had been another family in my life before them. I had always imagined that, when I revealed the truth, the ghost of my beloved would be the only mother-figure that the boys would have.

Clearly I was wrong.

I leaned a little closer to my muttering son. There were other words sprinkled amongst the gibberish, such as "tunnel" and "wall". Was Michelangelo having a disturbing dream, brought on by illness, of his fascination with the small run-off section of our Tunnel 49? This seemed the most likely option, but still, my heart was troubled.

The night seemed to last an eternity.

Excerpt from the diary of Hamato Yoshi, 27日, 9月.

Eventually, the morning came. Those of us well enough to sit up did so, and gathered around Michelangelo. The child seemed to fare even worse, if possible. I feared that we were losing our youngest to this sudden, fierce sickness. My eldest sons could clearly pick up on the fact that something was badly wrong; they trembled and crowded around their little brother with a desperate anxiety that was terrible to see in such young children.

I did all I could for Michelangelo today. However, he continues to deteriorate, and mumbles near constantly about tunnels, walls, and someone called Mama.

If it is the last wish of my son to return to that place, I will grant it.

…

I carried Michelangelo in a sling on my front, with Raphael, Leonardo and Donatello toddling along beside me. Thankfully, the walk is not a long one. As soon as we got within sight of Tunnel 49, Michelangelo began behaving very strangely. Showing more spirit than he had all night, he struggled wildly in my arms, nearly tossing himself out of the sling. I tried to calm him, but his cries of "Mama! MAMA! Wall! Maaaama!" overpowered my attempts.

"Ok, little one, I will take you to the wall. Please, hold still…"

My words didn't seem to get through. With a stern warning to my other sons to "stay put", I carried the wriggling infant down the side tunnel that had so fascinated him those two nights ago. When I had walked a short distance, he suddenly quieted, his eyes riveted to a crack in the mortar of the bricks. I shivered. It was much colder in this part of the tunnel, though I had left my eldest sons within sight in a pool of autumn sunshine coming through the broken grate. The boys seemed fine, if a little curious as to what I was doing with their little brother. Looking back at Michelangelo, I found him straining with all his might to reach the small crack in the wall.

"Mama," he wailed plaintively. "Get Mama!"

"My son, there is nothing there. Look at Daddy, come on."

But he continued to ignore me, as though I were as inconsequential as one of the many flies buzzing around our heads. The knowledge hurt, and I am ashamed to say that my temper, worn thin by anxiety and a fractious, broken night, got the better of me. Setting Michelangelo down out of harm's way, I aimed for the loose mortar, and executed a powerful strike. Over the sounds of crumbling brick, I heard my children squealing in panic. I scooped Michelangelo up, coughing, and immediately turned, calling back down the narrow tunnel to reassure them.

"It is alright, my sons. I was just showing Michelangelo that there is nothing—"

A foul stench assailed my sensitive nostrils at the same time as a noise, an odd, chittering, creaking sound, made my ears fold back against my head. The hackles along my spine rose as the animal instinct of fear rarely felt rose over me.

I did not want to look back.

I did not.

I did—

My jaw dropped in disbelief as, with an erroneous crunching sound, a dirty, yellowish mist coalesced in front of us. I was aware that such things must exist; the existence of yurei; human ghosts. I was instructed in the Shinto religion when I was a younger man.

However, the sight of such a creature in front of me had almost paralysed me with terror. It wasn't until the bundle in my arms chirped "Mama!" and the mist pushed forward slightly in response, that I rallied. Clutching my child protectively to my chest, my lips drew back in an animal snarl as I spat the familiar words of the Kuji-in; a purification chant that should, at the very least, buy us some time.

The presence let out an enraged screech, and dissipated enough for me to bolt through, scoop up my wailing sons, and run back to our home with them clinging desperately to my fur. As soon as I cleared the turnstiles, I set them all down on one of the couches, and sprinted to my dojo. I had kept some relics from my days as a practicing ninja in Japan; one of which being a shimenawa rope festooned with shide papers. These had been used in purification rituals for centuries in my homeland, and though I had no idea they would work, my frantic mind saw binding the spirit as the only solution.

I wrapped them hastily around my body, and fled from the lair, ignoring the heart wrenching calls of my dear sons with great difficulty. The sense of wrongness festered even more strongly in the crumbling tunnel, and seemed to block out the sun itself. Diving in with only a shimenawa as protection suddenly struck me as foolhardy, but as the mist coalesced in front of me once more, I could feel a vague sense of distress beating at my spiritual mind.

"You," I snarled, advancing and backing it toward the hole from whence it came, "will leave my son ALONE!"

I recited the Kuji-in once more, strengthening the chant with my own rage, fuelled by the furious, protective love of a father toward his sons. The spirit gave one more choking cry, and seemed to get sucked back through the crack in the tunnel wall. Wasting no time, I continued to speak the ancient words as I hastily placed the bricks back in an approximation of their original formation, and tied the shimenawa to two dripping pipes sticking out of the wall.

Immediately upon speaking the last words, the presence vanished. The change in the atmosphere was so abrupt that I fell to my knees, panting. Was that really the end of it? Was it over? Would Michelangelo—

"Michelangelo!"

Forcing my exhausted body to move once more was excruciating, but I reached the lair in record time. I could hear excited chattering coming from the living area; Raphael was laughing, Leonardo was squealing loudly, Donatello was speaking fast, joy in his voice, and Michelangelo…

I ground to a halt to witness my youngest son being propped up by his brothers, kissing every face that he could reach with the enthusiasm that I had so missed. He looked up at me, eyes sparkling with life.

"Daddy," he chirped. "I'm hungry!"

Excerpt from the diary of Hamato Yoshi, 28日, 9月.

Today, I boarded up the entrance to Tunnel 49. We shall not play here again.

The giant rat closed the faded diary with one paw, and beckoned the two strangers forward with the other.

"Now, you have heard the tale of how we came upon this tragedy."

Sighing gravely, he massaged his aching temples, then looked up, eyes bright with reluctant hope.

"Tell me," he began.

"Can you save my son?"

A/N: I love Splinter, but my goodness, his POV in diary form really took it out of me! I hope you enjoyed this prologue! I'm off to New York myself tomorrow, so I'll be able to get a real feel for the next chapters!