This story is by Jimmy (his pen name is 'Jimmy Attackles Veni's Leg' currently) and me. It is not put on a joint account because joint accounts are a big hassle.
We originally intended it to be for a writing challenge, but it got to be a bigger project than just a one-shot. It will be a multi-chapter story that is three to six chapters long.
As a final note, we based the disease in the first chapter off Necrotizing Fasciitis which is a flesh-eating disease caused by bacteria. :D

Once upon a time, a she-cat who was rotting on her paws limped across a log into ThunderClan territory. A tree had fallen over the river in the last night's storm and now acted as a bridge for the creature. A patrol of ThunderClan warriors smelled the stench of death and decay carried by the wind before they spotted her. In unison, their heads turned toward her direction and they watched in shock as she staggered toward them.

The fur on her leg seemed absent; her skin discolored into a sallow shade of yellow. A patch of it had peeled away entirely, exposing blackened muscle and thin, arthritic bones. Where were the well-defined muscles of a warrior and the strong bones her peers took for granted?

Gone.

For the most part, at least, she was empty.

Cast out by the Clan she had always called home when her flesh began fading away inexplicably, she had nothing. No one could help her, not any living medicine cat. Her Clan did not want the disease which rotted her body to taint their lands, so she was sent away. No den, Clan or mate to call her own for however many miserably painful days she had left.

When her paw first touched ThunderClan's territory, the shocked cats regained control of their limbs. The leader of the patrol narrowed her icy eyes and crouched low to the ground as she crept toward the she-cat. A dark brown tabby tom and a thick-furred white tom followed close behind her. The cat coming on to their territory paid them no mind and staggered down from the log. The ThunderClan patrol crept slower as they neared her and stopped a few fox-lengths away from what seemed to be a living corpse.

"What is it?" the brown tom growled in a low tone.

Noticing the patrol for the first time, she cocked her head and replied with a hiss, showing her nearly snow white gums to the stunned ThunderClan patrol as she meowed "Who is she?"

"What does it want?" the white tom asked, his eyes turning from the dying she-cat to the leader of the patrol.

"What does it want? It wants to be understood. It wants comfort in its last moments." A thin line of blood dripped from her emaciated lip and landed on a blade of grass, staining the land as she snarled.

"Don't listen to this, this . . . thing. She could be contagious," warned the other tom, with a hint of urgency to his voice.

"Bluestar, you will help me, won't you?" she asked, wincing as she limped toward the she-cat. Bluestar stepped back as she approached.

"Are you afraid of me?" The decrepit, diseased cat stared at Bluestar, her pale yellow eyes seeming to sink and dissolve into Bluestar's fur.

"N-no, I'm not afraid of you." Bluestar's tongue stumbled over the words. The brown tabby let out a low-pitched growl from behind her.

"RiverClan was afraid of me," she said, meeting the leader's eyes. "They tried to help, but only for a while. Mudfur couldn't figure it out, so he asked the other medicine cats to help. They couldn't either and I was starting to stink. And that's when they decided to get rid of me. They said it was because I could spread it to the kits, but they cast me out because they were afraid for their own pelts. Nothing more.

"No one else's flesh started fading away. No one but me has dealt with this pain. No one can be infected by me or the rest of RiverClan and your medicine cats would be rotting in their bodies too. I am not contagious, just ugly and that's why my Clan is afraid of me; that's why your friends here are afraid of me. And that's why you're afraid of me."

"This must be the case Spottedleaf told me about less than a half a moon ago," Bluestar whispered to the rest of the patrol. "She said there was a case in RiverClan that nobody seemed to be able to cure. Spottedleaf said the cat was going mad from the disease eating away at her flesh and such a high fever." The white tom nodded, but the tabby's eyes were fixed on the RiverClan she-cat.

He took a step forward and snorted a little. "I'm not afraid of you. Being scared of you would be like fearing a mouse."

The gray cat lunged forward on unsteady legs. Her hissing mouth was suddenly but a tail-length from his face. He scurried backwards, trying to get away from the cat that reeked of death.

"Let me come to your Clan. Let me die on a bed of soft moss with poppy seeds to ease my pain. Let me die a warrior and after I die, let me be buried as a warrior too. Will you do that for me, Bluestar? Will you let me go to StarClan as a warrior?"

The leader's gaze turned from the she-cat to each of the toms as she looked for something, some sign to tell her what she should do. Compassion is a long way off from doing what's best for the Clan. . . .

"I won't stay long—I'll be dead in a few days," the rotting she-cat added with a hoarse mrrowof laughter. No one laughed but her.

Bluestar let her gaze drift back towards the two toms. They were trusted warriors. Shewas a massive risk to the cats she devoted her her life to protect. StarClan knows she really has given her life for her Clan.

"We should kill her," the dark brown tabby meowed, meeting Bluestar's gaze "She's already dead. It's only right to kill her."

"She's not dead or she wouldn't be begging us to take her her in," the white tom countered. "How can a dead cat talk?"

"I don't know how she's talking, Whitestorm, but I know that she isn't alive. No corpse has ever walked this forest and it's wrong to let one walk it now." The brown tabby spat with frustration.

"If she is dead, she's a warrior of StarClan. How can we kill her if she is just that?" the other tom hissed, his fur beginning to bristle.

"What is a warrior of StarClan doing out of the skies? She's dead, but she's not of StarClan. You of all cats should think it best to put her out of her misery—to let her join them."

Whitestorm turned to Bluestar, meeting her eyes. "Bluestar, we should let her stay with us. If she's not dead, she deserves company and to be part of a Clan in her final moments . . . and if she is of StarClan, killing her could bring about the destruction of our Clan."

"You might be right," the blue-furred cat meowed, turning her head to the sick she-cat. "Tigerclaw might be right too."

"Tigerclaw, is it?" the rotting cat purred, drawing closer toward him. "You want to kill me? I dare you to. I dare you to kill me with your own claws. Dirty your fur with my stinking flesh. Kill me, Tigerclaw."

Tigerclaw's gaze moved from the dying she-cat to Bluestar and back again. Bluestar finally opened her mouth.

"What is your name, she-cat?" Bluestar asked, drawing the sick cat's attention away from the trembling tom.

"My name is Graypool, formerly of RiverClan, Bluestar." She started to slowly creep towards the leader instead.

"Tigerclaw, you won't kill her." Bluestar paused slightly, her voice wavering as she spoke again. "But she won't find her death-nest here. Not in my Clan," mewed Bluestar definitively.

Graypool turned her head to her former home before looking back at the blue cat. Her tail twitched as she hissed "StarClan came to me in a dream the night before RiverClan cast me out. They said 'Go to ThunderClan. Their leader will take care of you for the rest of your short days. You did so much for her.' I'm not sure what I did for you, Bluestar, but I have a suspicion. I went to Gatherings so many moons ago. I saw you sharing tongues with a tom. The very same tom who—"

"Quiet!" ThunderClan's leader hissed, crouching on her paws and baring her teeth.

"You'll wish that you had let me go on, Bluestar. I promise you that."

She lunged at Bluestar. Bluestar shook as she saw the she-cat race toward her, but the leader stood her ground. Graypool didn't make it to Bluestar and sprawled on the forest floor less than a tail-length short of the ThunderClan leader's feet. She tried to get herself up, pushing with all the strength she had in her feeble, deteriorating old bones, but her limbs finally failed her.

But still, her will remained alive. Her heart gave out; her body was starting to grow colder; blood ran freely from her mouth to the ground, traveling in a slow downhill stream toward Bluestar. Bright points of light began to form on her dirty gray pelt as StarClan took her. Her eyelids opened and shut over her yellow eyes, even though she was dead. It was pure will that kept her other-worldly body in her Earthly corpse as she growled her dying words.

"Bluestar, the mighty leader of ThunderClan, is afraid of me. You're not afraid because you could rot away in your own body, are you? Every cat does that eventually. You're afraid, like your friend, to be as ugly as me. You're not afraid to rot in your own skin, you're afraid that the rotting will leave you repulsive and friendless—Clanless—like me. You deserve that. To have what happened to me, happen to you and to have no one to help you or love you.

"StarClan, if you were to let me have me anything in my miserable life, please let me have this."

Bluestar, transfixed in horror as the stars forming on her pelt glowed brighter and brighter. As she talked, a thousand voices were added to her own; her final words were meowed with all the wrath of StarClan.

Her limbs felt frozen until she watched as Graypool's yellow eyes close for the very last time and the stars fade from her fur. She turned to Tigerclaw and Whitestorm then.

She did not talk, just flicked her tail toward them and started padding back to camp. After a few paces she noticed something strange: the lack of pawsteps behind her. "Keep up," Bluestar mewed impatiently, but she hardly understood her mutilated words. Her eyes turned back to her Clan mates and she found that they hadn't moved a paw. She quickly repeated her original orders, this time verbally.

"Come on, back to camp!" said Bluestar, a slight hint of anger in her words. She found again that her voice came out strangely. It was low, hoarse and as loud as the monsters on the Thunderpath.

Slowly, she walked towards the toms, an uneasy feeling forming in her stomach. "Tigerclaw, Whitestorm, what's wrong?" she whispered, but it came out as a roar. She noticed their bellies didn't move with their breath, their fur didn't part with the wind and their whiskers didn't tremble at all. When Bluestar drew close enough to see their faces, she saw twin expressions: jaws agape and unblinking eyes wide with shock. Her eyes drifted from the toms to the dead she-cat lying on the forest floor, the diseased she-cat who died at her paws. Graypool's spirit seemed to climb out of her body, the spirit's fur filled with stars. She daintily sat upon the forest floor, emitting the collective purr of her ancestors, looking at the scene before her for a moment and admiring the great favor StarClan had done for her.

Bluestar picked up pace and headed toward the river, moving her legs faster and faster until she was galloping toward the water. "Could it be real?" she said over and over again, her rumbling voice filling the forest. When she reached the water's edge and peered at the reflective waters, she stumbled back. "My Clans, my life, my friends . . . all gone."

Bluestar now knew Graypool's words to be true, for she had seen a monster in the river.