Disclaimer: I do not own Harry Potter

...

"Alright Harry, if this actually hurts you, just know that I'm sorry," said Hermione as she lifted up her wand and pointed it directly at the teenage boy who stood there with his left arm raised in front of his chest, his fingers clenched into a fist. Ginny stood nearby, biting at the inside of her lip to prevent herself from hyperventilating.

It was a tense and unpredictable scenario to say the least.

In an unfamiliar classroom the trio of children had pushed all of the tables and chairs to the far corners of the room to ensure that they gave themselves plenty of space if anything went wrong. Since they were playing with ancient magic they felt the precautions necessary. It was also why they had chosen a room only a corridor away from the hospital wing.

An Autumn drizzle would keep a majority of the students inside the walls of the castle so they hoped that nobody came across what they were doing. It was a risk but they all knew that something had to be attempted in order to prevent something catastrophic from occurring, or so Hermione believed.

She had approached them the previous night and related their possible problem to that of an overflowing cauldron with magic still being pulled into the enchantment to the point where it was starting to overflow. Harry and Ginny had both agreed that if that was indeed the case then they would do something about it the following the day.

Hence how this situation came to be.

Hermione braced herself before she shot her curse forward, nothing dangerous but enough to see whether or not the charms they originally cast on the potion were active. "Petrificus Totalus!" she bellowed as the spell rocketed forth. Harry, understandably, had had his eyes clenched together as to not look the curse in the face. Having never been struck by this particular spell, he was unsure as to what sensation was meant to pass through his body. Complete movement was not what he expected.

"What happened?" asked Ginny.

"It didn't work," said Hermione as a smile grew upon her face.

"So what does that mean?" asked Harry.

Hermione responded by firing another curse at him. Ginny got in on the action as well. Good times were had.

Minutes passed by as Harry, Hermione and Ginny fired spell after spell at each other, exhausting their magical knowledge and firing every curse and hex they could think of. Unlike the nasty or painful results the spells should have inflicted, the only response was a small stinging sensation or a much less noticeable result. Through their playful session they did discover quite quickly that only when the spell made contact with where their tattooed curse was located was the spell completely nullified. The further away, such as on the other arm, legs and head were where the most effect was had, but even then with spells that were meant to create a rash there was nothing more than a freckle sized skin irritation, one which would vanish minutes later.

Of course, happy times didn't last forever as Ginny cast a cutting curse at Harry, expecting a scratch at the worst. Sadly, that wasn't the case.

A gasp of pain escaped Harry's lips as blood splashed across the floor, Hermione and Ginny gasping in shock and they dropped their wands as they rushed to where Harry was. "I'm so sorry!" apologized Ginny. The curse had sliced across Harry's arm, the one that wasn't etched on with the (supposed) Celtic brand.

Harry gripped at the gash, blood seeping through the gaps between his fingers as he did his best to keep the pressure on. "We need to get you to the hospital wing," declared Hermione.

"Wait," said Harry, startling both the girls into quiet. Harry stared intently at the wound. Seconds ticked by before he released his grip, Ginny nearly losing her lunch at the sight of the bleeding wound.

"You need to put pressure on it Harry," stated Hermione, but the Boy Who Lived could feel something other than pain at the moment. He had a theory and he needed to check it out. The other week when he had been attacked by Buckbeak, he had cut himself on both arms to test out if there was a difference in recovery. While his left arm had stitched itself together like he had predicted, his right arm had not. That being said though, come the following morning there was no indication that he had been cut at all.

Slowly, his theory proved true as the skin which had been severed started to move on it's own accord, patching over what had been torn flesh. It was nowhere near as quick as it's counterpart, taking the better part of five minutes to fully seal a wound which had been no wider than a quilltip, during which time neither of the three students moved a muscle. "Did you know that would happen?" asked Hermione, the first one to recover.

"No," answered Harry bluntly. "When Buckbeak got me the other day the wounds were a lot bigger, but on the other arm. I watched as strands of muscle sewed itself back together..."

That was as much as Ginny could handle as she kneeled over and the contents of her stomach exploded onto the floor, Hermione quickly bending over and holding the red haired girl's hair behind her head. Harry having had his statement cut off, turned his attention back on his arm as his mind worked overtime trying to come up with several possible theories he needed to test. At the moment he hypothesised that this magic was like a muscle, the more it was used the stronger it would get until the rest of his body was as enchanted as where the markings were.

It was a theory, one which would require a lot of painful activities in his own time. With Sirius Black potentially after him, however, he would need every advantage he could get his hands on.

...

"That'll be detention, Mister Potter, for showing such vile artwork during class," declared Snape as he caught Harry looking at the intricate design on his arm. As soon as the trend had reached its peak in popularity it quickly became known that the Potion's Professor was by no means a fan of what was happening, and would punish those who showed a trace of ink upon their arm. While many of the students quickly found themselves purchasing Vanishing Ink, yet another brilliant creation by the Weasley twins, there were three students who such a thing would not work. "To teach you to clean yourself up you will scrub the floor after class until I am satisfied."

Harry meanwhile couldn't argue against the rules that the Potions master had put into place and grimaced at the fact he would be spending time after class in the presence of his least favourite teacher. It wasn't as if he had intentionally showed off the marks, but he'd been dropping Mermaid Scales into his cauldron and his sleeve had rolled down his arm. It was an accident, but still.

Looking over his shoulder he could see Draco Malfoy sniggering away. With an exasperated sigh, Harry once again focused on the task at hand. Thankfully the class would finish within the following fifteen minutes, Snape saying that Harry's potion was 'adequate for someone of his skill level.' Harry wasn't sure whether he was being complimented or insulted.

As he watched his fellow students leave, Harry made his way over to the stationary cupboard and pulled out the mop and bucket. With all the housework he had been forced to do during his childhood, this wasn't as much of a punishment for him compared to other students. Of course he wasn't going to tell Snape that.

Harry worked away diligently while Snape sat at his desk grading essays, every so often glancing at the teenager to ensure that he wasn't slacking off. The professor, like every other teacher in the school, had been informed by Dumbledore that what was happening with the three Gryffindor students was a delicate case that should be handled with caution. Snape meanwhile would not provoke the student population by permitting Harry to get away with something he punished everybody else for.

He would die before showing favouritism to the Potter boy.

The sound of the wooden mop crashing to the floor made Snape's head snap, up but before he had a chance to berate Harry for his clumsiness, he could see the look of silent agony on Harry's face as he gripped at his left forearm. With a primal yell, Harry did his best to contain whatever it was that was going on but even Snape could see that Harry was in a lot of pain. Sadly he was too late to do anything, by the time he stood up from his bench he could tell that he had missed whatever opportunity he had.

A vicious gale began circulating around the room, paperwork being tossed in every direction as Snape and Harry's robes danced in the wind. As quickly as it had begun it vanished, but it was not the end as Snape found himself bowled off his feet by a powerful gust of wind reminiscent of a tornado's fury. Clamoring to his feet, Snape readied himself for the next instance but considering that Harry no longer looked like he was in pain he felt like he was in the clear.

Harry meanwhile had bullets of sweat streaming down his face as he did his best to get his breathing under control, his heart pounding in his chest. He had no answers for what occurred but it had been much more painful than his previous attack, as if the magic itself had been trying to rip through his skin. It hadn't been the burning sensation he had felt before either, he didn't even know how to describe the pain he had felt.

"Mister Potter," said Snape, his voice cold and calculated. He crossed the distance between them in a matter of seconds, looking down at the teenage boy with something similar to disgust in his eyes. "Explain."

Harry had no answer.

...

Dumbledore was silent as Harry finished retelling the events that had unfolded down in the dungeon as well as what he, Ginny and Hermione had been experimenting with the previous day. With his fingers laced upon the desk, the Hogwarts headmaster could see that Harry had been trying desperately to figure out in his own way what it was that was upon his arm. Dangerous to say the least, but Harry had been quick to add that they had done what they could in a controlled environment. Of course this had simply made Albus curious as Harry refused to go into more details. Had the young teenager merely forgotten something or was he withholding on potentially valuable knowledge.

Whether Harry was deliberately concealing information for one reason or another didn't matter, Dumbledore through all of his years and experiences could tell that Harry was mishandling possibly crucial knowledge. Information that could be vital to the boy's survival. Probing the boy for more intel would likely be pointless, so while the Professor hated using it, he silently activated his Legilimency and began to invade the boy's mind.

His will was not menacing, merely inquizitive, and he couldn't tell whether it was because he hadn't used this skill in such a long time that when he probed the boy's memories he was not shown anything reminiscent to what he had been told. Looking around, he couldn't even spot Harry amongst the dungeon-esque room he was standing in. There were no doors, no windows yet he could see clearly the black paved pricks that made up the floor, walls and ceiling.

Just where was this?

"Get...out!"

It wasn't a suggestion, it was a command.

Before Albus could locate the speaker he had been thrust out of Harry's mind at such a pace that he found himself knocked into the back of his chair, his eyes fluttering as he tried to comprehend what had just happened. He wasn't even able to hear Severus and Harry question him if he was alright or not, he was far too concerned with the voice that had thrust him out of Harry's mind, if that even was Harry's mind.

The voice had been cold and void of life, yet even as a whisper it had had such raw power behind it that Albus dared to question what would have happened, had he had actually had the power to stay. He had searched every crevice the room had prior to being ejected and he had not located anything resembling life.

There were two things Albus could contemplate the reasoning behind this was at that moment, undoubtedly he would spend the next several nights debating with the former Headmasters lining the walls for their opinion on the matter. Firstly, Harry was a natural at Occlumency. Unlikely yet plausible at the same time, the scar Voldemort having left being a natural guard to mental attacks.

The second option he could see however, was much more dark in nature. Perhaps the mind he had entered hadn't been Harry's at all. Dumbledore's glance looked down at the spell engraved onto Harry's skin, Snape and Harry following his gaze to witness as the previously black lines pulsated red as if in warning. While this was a theory it was one he could not tell Harry no matter how dangerous it may be.

The spell was sentient.

...

Hope you enjoyed, special thanks to kalebxdd for betaing my work