Disclaimer: I don't own anything, J.K. Rowling created the Potterverse; I just play here.

"What are you doing here, Potter," Snape sneered as he caught the intruder walking across his foyer. He recognized the boy immediately, although he wasn't a boy anymore. The brat had matured, he was taller, older. Even so, he still had the same messy hair, Lily's eyes, and telltale scar on his forehead that made identifying him all too easy. Snape found him to still be exceedingly arrogant, sneaking around his house.

He had first been alerted to the intrusion when the amulet hanging around his neck glowed a bright red, meaning that someone was inside his house. He immediately went to a secluded place and apparated back home, only to find Harry Potter striding through his foyer. He obviously must have incapacitated Fennel, his security system fashioned from a dragon statue.

As soon as he had spoken, Harry whirled around to face him; looking like a child with his hand caught in a jar of Cockroach Clusters. "I need your help," Harry stated, not intimidated by the glare on Snape's face.

"Why should I help you?"

"If I had any other option I wouldn't be here," he explained, his hatred for his former Professor rising.

"That did not answer my question," Snape replied coldly, stepping around him to enter the room Harry had just vacated. "Especially since you have violated my home and assaulted my security,"

"That little dragon thing was your security?" Harry asked, incredulously. "He was a pushover,"

"He served his purpose, warning me of an intruder," he explained, returning the dragon statue in question to mobility. "He was also to keep you distracted until I could arrive,"

"I'd say he failed miserably at that,"

"You only observe the very obvious, Potter. That is one of the reasons that you were so atrocious at Potions. Did you stop to think what would have happened if he hadn't intervened? He delayed you just enough so that you didn't have the time to make it further into my home before I could arrive," He explained in his most condescending voice. "Are you going to explain what you need help with or are you going to attempt to further insult my house,"

"I have a problem," Harry said, taking a deep breath as the prepared to launch into the full story.

"I was able to figure that out, what I need are details,"

"Let me finish," he protested.

"Well then finish, unless you'd rather waste my precious time further," Snape leaned against the door frame of his living room, observing Harry with the same coldness and contempt that he had always had for the brat; even after the fall of Voldemort.

"When the sun goes down-" Harry was interrupted by his alarm watch screeching to announce that the sun was indeed setting and he had only moments before the change would begin. "I think you're about to see,"

Snape said nothing but watched as Harry's face contorted in pain as he grew fur and transformed from a human being into a black panther with eyes the same shade of green that they had been when he was human. His cry of pain turned into the inhuman growl of an animal, what he had become.

Snape had heard changes like this mentioned in some of his oldest Potions tomes, human by day and animal by night. There had even been mentions of it in Muggle fairy tales, evidence of a botched coverup by previous Wizarding generations. He would have to pull out some of his older books to do research. He knew that he would help Potter, he had saved his life in the final battle and this would be a way for Snape to repay him, plus he hadn't had this type of challenge for years.

"Very well, Potter," Snape addressed the panther, who was looking at him as if he had expected an answer. "I will help you. Do try not to leave claw marks in my couch,"

Harry growled in response, but accepted the invitation to stay the night and curled up on the couch; falling asleep quickly without the distracting sounds of drunken melodies the floor below him.

Dawn came. He wasn't expecting it, and his watch didn't alert him to it because it had become fur and did not have the capability to alarm him, and so he managed to tear up one of the cushions of the couch and a great deal of the floor which he rolled onto sometime during the change. Human again, he lay on the floor, among the ruins of what was once carpet, for a while before getting up and surveying the damage.

Usually he didn't destroy furniture, but then usually he was not spending the night on the couch of one of the men that he hated most in the world. He was fairly certain that his anger was the cause of the destruction, that and him being caught unaware when dawn came.

"I thought I had told you not to demolish my couch," he turned around to see Snape standing in the doorway.

"You said not to get claw marks in it. I ripped it apart, there is a difference and you didn't even mention anything about the carpet," Harry smirked, glad that he had lost control at the look that was residing on Snape's face.

"Reparo," Everything was fixed and looked like it had never been damaged at all.

"What's for breakfast?" Harry asked, feeling a sudden surge of boldness.

"There is not going to be any," Snape said, getting satisfaction from Harry's disappointed face. "I assume that you are capable of securing your own breakfast. Or am I overestimating your abilities. Do your talents not extend to procuring meals?"

"I think I've had enough of you lobbing insults at me," Harry stated. "I think I'll just leave, owl me when you've got the potion ready,"

"Then you will never receive that owl,"

"What? Why? You said you'd help me," he protested.

"I will need some information before I can begin to brew," Snape clarified. "I cannot be expected to make such a complex potion with as little knowledge as I have now,"

"What do you need to know?" Harry asked.

"How did this happen?"

"Sometime during the fight with Voldemort," Harry noticed how he cringed slightly when he said the name. "I don't know exactly,"

"I said how not when," Snape reminded him coldly, still able to make Harry feel inferior although he was no longer his student. "Are you too thick to make the distinction between the two?"

"I don't know how. I didn't even know that it had happened until when I woke up in St. Mungo's a week later," Harry said, his voice carried a hint of sadness. "I had transformed in my sleep every night. They had to put me in a special ward. Anything else you need to know?"

"Do you recall what happens at night? Or are you like your beloved werewolf, unable to control yourself when the moon rises,"

"It has nothing to do with the moon, it's the sun," Harry contradicted him. "And yes, I remember everything, I have control over everything,"

"I have all that I require. You may, as you previously expressed the desire to, leave,"

"When will you be done?" Harry called out, seeing Snape retreating into the recesses of his house.

"The first trial should be done in a little over a months time,"

Harry was disappointed that he would have to wait over a month for just the first trial, he wanted results quicker than that. He knew that he had no other choice, so he apparated back to his flat in London and went into the kitchen to make breakfast for himself; not because he was hungry but because Snape had made him feel incompetent. By making breakfast he proved to himself that Snape was wrong about him, like always.

The following weeks passed by in a blur, each day blending into another. He dragged himself to work, acting as an assistant to Fred Weasley at his joke shop. George had perished in the war and left Fred to managed the shop all by himself so he had offered to hire Harry when he found out that he was looking for work. It was mostly to keep busy, and Fred let him have an erratic work schedule so he could pursue a cure.

He was expecting an owl from Severus Snape, and was surprised when he sent the miniature green dragon to him. He had a letter clutched in his muzzle and looked rather worn out when he arrived on Harry's windowsill.

"Fennel has arrived," he announced proudly before collapsing onto the floor, taking the letter along with him.

"I need the letter," Harry impatiently told the dragon.

"Fennel will let the brat have it," and he released the piece of parchment into Harry's hand.

"Brat? You've been listening to Snape,"

"Master is wise on all topics," Fennel proclaimed proudly as he made a big show of lifting himself off of the ground.

"Teacher's pet," Harry muttered, reading over the note.

The first trial is completed

It wasn't even signed, although Harry knew it was Snape. It had only been three weeks, he must have finished it early.

"Master sends Fennel to tell pest that he should apparate immediately," the dragon ordered.

"Brat, pest. Can't the greasy git some up with something more inventive?"

"Master is not greasy!" Fennel protested, leaping up into the air and attempting to set Harry on fire.

Harry just rolled his eyes and apparated into Snape's foyer. As he expected, it was empty. He hadn't really thought that Snape would be waiting for him when he arrived. Harry did not have the slightest inkling where the greasy git was so he decided to go out and search for him.

It was not likely that this trial would work, so Harry tried not to get his hopes up. Years of disappointment aided him in this endeavor, but there was still that little bit of hope. It was near sunset, obviously Snape had waited to send for him so that they did not have to wait a long time before being able to see the results.

"Potter," the familiar voice of Snape shouted from behind him as he had just begun to walk up a flight of stairs. "Where are you going?"

"Looking for you,"

"I have been in my workshop," he stated.

"Where's that?" Harry asked, looking around.

"Follow me," Snape ordered, turning around and going down a long hallway; robes swishing behind him.

They went down a hallway, then turned and went down stairs into what must have been the basement. It looked almost identical to a Hogwarts dungeon, with several cauldrons full of potions all in various stages of developments. A plethora of smells assaulted Harry's senses, almost immediately his eyes started to water from the smoke coming off of one of the potions.

"If you feel the need to cry I would rather that you take care of the urge somewhere other than my personal workroom,"

"I'm not crying!" Harry argued. "It's the smoke,"

"Then do not be so daft to stand right over it," Snape grabbed Harry's arm and pulled him away from the potion. "Standing too close to that particular potion while it is being made will cause fainting,"

Harry had only stood near it for a short while and he already felts slightly woozy. "I see that," he swayed a little before feeling his head clear and was able to regain his footing.

"These are the first trials," he gestured to a row of seven potion bottles, all various shades of green. "It will take a week to test them all, and then I can begin to make adjustments,"

"Trials?" Harry asked, he had only expected one.

"Yes trials," Snape replied. "Did I not tell you that I would be making more than one at a time?"

"Which one will I test first?"

"This one," he pointed to the first one in the row, it was a deep green. Forest green, Harry decided was the name for that particular color.

Harry reached out and grabbed the first bottle, uncorking it and drinking it all in one gulp despite its horrid smell and taste. "You did test these out first, right?"

"There was no need,"

"What do you mean 'There was no need'?" Harry asked worriedly. "I could be sprouting several heads or turn blue,"

"The ingredients I used have no danger of interacting with each other in a way that would cause side effects," Snape elaborated. "That is what I meant by 'There was no need',"

"It's nearly sunset," Harry stated, looking at his watch.

"Get out of my workshop," Snape ordered. "I can not have you transform and destroy my valuable potions and supplies,"

"I'll just destroy the rest of your house then," he muttered in reply as he left the workshop followed shortly after by Snape.

Harry walked into the living room, waiting for the change to overtake him and to find out if the potion worked. The alarm on his watch went off, and a few minutes passed. Nothing happened. Harry's heart leapt into his chest. The sun was down. He was still human.

"It worked!" Harry shouted, feeling elated. "I can't believe it worked,"

Just as Harry was celebrating, he felt the immense pain associated with the change. He looked down in horror as his clothes changed into fur and spread over all of his skin. He did not understand, why had the potion not cured him. It had seemed so before.

"It appears that the particular dosage I gave you only delayed the change for a short while," Snape said to the growling panther. "I have stronger ones. The goal is to delay the change until sunrise so that it never happens," the Harry panther gave one last growl and walked down the hallway, into the living room, and onto the couch where he fell asleep.

The reversal of the change took place right at dawn, Harry was relieved that it was not delayed as well. This time he did not tear up the couch, only the carpet and he fixed it with a wave of his wand before Snape even saw it.

"Are you going to let me have breakfast today?" Harry asked, coming into the kitchen where he found Snape seated at the table; drinking the same potion he had seen him take all those days ago when he had first sought him out for help.

"Only if you make it yourself,"

"I will," he walked over to the row of cupboards lining the far wall, rummaging through them in search of food. They were almost bare, there were more cobwebs than actual food. "Don't you eat?"

"Yes, I do," Snape downed the last of his potion and sent it to the sink. "I just have not had the time to go to the store,"

"Well, then I'm going now," Harry declared, walking out of the kitchen. "Just because you enjoy starving doesn't mean I'm going to endure it,"

Twenty minutes, several galleons, and one trip to a Diagon Alley grocery store later Harry was standing in Severus Snape's foyer with a half dozen bags of groceries floating around him. He went into the kitchen, from which Snape had vanished, and put everything away. It had occurred to him to simply apparate back to his apartment and make breakfast there, but usually when he changed he did not have the energy to apparate too much. He figured it to be easier to simply make one trip to Diagon Alley so for the remainder of the week he could eat here and get some energy so he could apparate to his apartment later in the morning without feeling so horrid.

"I'm about to collapse," he groaned as he sat down at the table and bewitched the cooking utensils to make bacon and eggs. He watched in anticipation as the plate floated over to him, in a way reminiscent of a flying saucer. Harry wolfed down it as soon as it had touched the table, being ferociously hungry.

After he had had his fill, he magically cleaned all the dishes he used and put all of the groceries away. He was tempted to just take off but he figured that first he would have to tell Snape that he was going, just in case he needed to be around for some reason.

The place Harry decided to check first was the workshop, it seemed the most likely place since the rest of the house seemed like it hadn't been lived in. He walked down the hallway, and then down the stairs, pushing the door open and finding Snape standing over a cauldron. He was pouring something over his left arm, the arm with the Dark Mark on it.

"What are you doing?"

TO BE CONTINUED…

A/N: I'd just like to say thanks to my beta Rebecca Robinson, and all of my reviewers-you guys rock!