It should be mentioned that I do not own Harry Potter. I can only thank Rowling for this sandbox that so many individuals, myself included, get to dream in. I write only because I have read so many fanfics that I've begun having my own ideas that refuse to get out of my head.
The entire table was caught by surprise when suddenly without warning Harry began screaming. Everyone was frozen where they were unsure and uncertain of what they could possibly do in a situation that they had no understanding of. Even Mr. Hatterman was visibly confused in his shock at why Harry was screaming. However some level of understanding began to come as Harry went silent his head slumping forward, his chin hitting his chest before a moment later dark magical energy that bore a strong resemblance to clouds of silk erupted around him hiding him from the view of all.
Simultaneously the breaths of both Mrs. Tonks and Mrs. Malfoy halted their eyes widening in unison as they watched the slowly shifting cloud of dark magical energy. Dumbledore slowly rose from his chair looking from Harry at one end of the table to Mrs. Tonks and Mrs. Malfoy at the other. "Andromeda. You seem to have an understanding to what is happening to Mr. Potter. Would you please explain?"
Mrs. Tonks nodded slightly while across from her Mrs. Malfoy swallowed in silence, by this point Tonks and Draco were beginning to look pained in their expression but both remained silence as Mrs. Tonks took a moment to select her words. "It is the Black family magics. I do not know what is entirely going on but the family magic is drawing in the power of every member of the Black family no matter how distant. By now Mr. Weasley and you as well Headmaster should be feeling its effects."
Around the table the eyes of all widened turning to look at the still shrouded Harry. Hermione was the only one present who did not have a look of understanding. "I'm sorry Mrs. Tonks, what do you mean when you say that the family magic is drawing in magic. You can't possibly mean that your magic is actually going to Harry right now."
It wasn't Mrs. Tonks or her daughter who answered the muggleborn witch but rather Mrs. Malfoy. "That is precisely what she means you silly girl. This is ancient magic dating back thousands of years. The Family of Black is the oldest continuing line of magic users in all of Europe. It began as a coven that channeled the magic of thirteen witches into one, that magic has remained intact to this very day through all the generations. Warlock Black now has the power to tap into that part of the Black family magics that every living witch and wizard who contains the blood of Black in their veins. It seems that rather than Warlord Black calling the magics the magic itself is summoning itself to Warlord Black." She eyed the still slowly swirling magics at the end of the table.
"We are stuck here until whatever is happening is over. The goblins and their magic will not let us leave until Warlock Black is confirmed as head. I can only hope that whatever magic is being used will be over soon."
Beside her Draco was looking surly as he glared at everyone other than his mother in the room. Tonks and Ron matched him glare for glare. Mrs. Tonks however had the cold expressionless face that was a match for Mrs. Malfoy that he seemed to give up against, perhaps because he knew that expressionless mask was the equal to his mothers considering the two older women were sisters cut from the same cloth regardless of their husbands. Hermione simply looked back at Malfoy without reacting back an almost bored expression on her face. If Harry hadn't presently been surrounded by a cloud of magic she probably would have been bored but while she kept shooting worried glances at Harry's end of the table that did not mean she reacted to Draco's glares. He glared so frequently back at school that it had lost most of its bite on her. As for Dumbledore he simply sat there patiently avoiding the gazes of all the others his eyes still twinkling but his gaze fixed on where Harry sat. Mr. Tonks and Mr. Hammerman decided that prudence the better part of valor and took seat in a pair of chairs along the side of the room and like all the others settled in to wait.
Minutes passed without sound, nothing came from Harry in sound or motion as the could of magic continued to slowly swirl around him and the others sat there at the tables under fear of the goblins to try anything else. Even Draco seemed to realize how truly a dangerous place they were in given how effectively he was holding his tongue despite his very clear desire to speak. It was around the ten minute mark of sitting at the table that the first change was noticed. The slowly rotating and shifting cloud of magic began to grow agitated. Given how no less than half the eyes in the room had remained fixed on where Harry sat it was quickly noticed and Hermoine and Dumbledore alike sat up more slightly. Mrs. Tonks and Mrs. Malfoy had been sitting with perfect rigid posture the entire time although their heads too turned to watch.
Out of the clouds of dark magic swirling around Harry an ethereal snake composed of emerald and silver magical energies the same as the cloud emerged briefly in a loop only to dive back into the cloud. This caused everyone to take notice given how brilliantly the snake had shown with magical energy, a very potent and noticeable magical energy. For another ten seconds nothing disturbed the turbulent surface of the magic surrounding Harry before the snake briefly crested the surface once more, larger now, where before snake had merely seemed of normal size for an adolescent python now it was bigger, much bigger as its body was thicker now than and its head had been large enough to swallow the head of any of those present whole. The snake disappeared back beneath the surface of the rough magic still swirling more turbulently around Harry.
It was then that those sitting at the table heard a truly unnerving sound, not from within the storm of magic that continued to surround Harry but from around them as the goblins in their gleaming armor that had been stationed in the room drew their weapons. Metal scrapped against metal and Dumbledore lost the twinkle in his eyes at the sound and seemed to go a little pale. The goblins were not attacking anyone however, their gazes were fixed on the maelstrom of magic that swirled faster and faster around Harry. It was growing too and those sitting closest to Harry pushed back in their chairs to get away from it. The goblins did not fault them or warn them off as the gazes of all were fixed on the slowly expanding storm.
Then all at once chaos was unleashed as from the top of the ever growing cloud of turbulent magic that had beginning to flash with light came a truly massive serpent. It was easily over ten meters long and over a meter and a half thick at the widest point of its body. It flew out of the storm of dark wisps of magic as if chased by the hounds of hell. Its body gleamed with emerald scales, silver ones scattered amidst and its crimson eyes caused all but Dumbledore to pull back from its gaze. It did not turn its attention to them however as it landed on the far side of the room having flown over the table and all those sitting at it. Its gaze remained fixed and they could hear a soft hiss sound from it. Its very nature seemed to radiate an aura of fear for though it was composed completely of magic it seemed so real to the eye.
Those sitting at the table were not given long to study it though as a chilling howl that sent a shiver down the spine of everyone even Dumbledore included erupted from the still roiling storm of magic that surrounded Harry. A moment later a truly massive beast stepped out of the shadows of magic given form. With a massive body larger than any dog short of myth an enormous jet black grim emerged from the cloud walking one foot at a time around the table. The snake seemed fixated on the enormous grim and hissed at it, the grim of course growled back but no more than had the grim finished emerging but a truly magnificent sight emerged from the storm of magic at the end of the table once more. A shimmering and dazzling gryphon with crimson plumage and golden eyes stepped out of the storm of magic and walked around the other side of the table so that it and the Grim on the opposite side moved together on the snake.
Dumbledore was openly in shock and mumbled a quiet "Avatars? How...?" But found no answer coming from the magical beasts composed of pure magical energy. As the Grim passed Mrs. Malfoy she seemed almost as if she was in the throes of an orgasm as it drew near and in doing so lost for the first time her flawless mask that hid her emotions. The aura of the massive Grim as it moved past her was apparent and even Tonks and Mrs. Tonks on the other side of the table stared to the point that Mrs. Tonks's own perfect concealing mask that had hid her thoughts and emotions cracked as she realized what she was witnessing. "The Black Family Magic... And the Potter family magic..."
Before any answers were come the two magical entities representing the house magics of both Black and Potter leapt at the enormous emerald and silver snake. A battle was waged there on the far side of the room that none dared interfere in, no one after all missed when the gryphon's claws missed the snake and left gouges in the form of claw marks in the stone floor. The air thickened with magical energy so great it was like the humidity of the rain forests. To all the magic users in the room it felt to them that they were exposed to static electricity and if they did anything other than sit perfectly still and continue to breath the magic would zap them.
So the eyes of all watched unmoving except for the occasional blink as gryphon and Grim alike attacked the serpent. Even two on one the serpent did not go quietly. It was easily the largest creature and it used its size to its advantage but it was also stunningly quick as it maneuvered its body away from the danger of the gryphon's claws and the Grim's teeth. Still after the first twenty seconds it became clear that there would be a winner as whenever the Grim or gryphon would land a strike it its emerald scales would be ripped away by claw and by fang.
It was not over quickly and much of the far side of the room was left in ruin as the magical entities fought, the serpent thrashed while the gryphon and Grim alike raged against it. If not for the actions of two of the four goblins to advance and use an unknown form of goblin magic to create a powerful magical barrier separating the table and all who sat at it from the warring entities the table would have been utterly destroyed and many of those sitting at it dead simply as collateral of the fight.
Still the seconds of the fight turned to minutes and though all could not take their eyes off the spectacle that was happening before their very eyes as they sat transfixed it had to draw to a close. It ended with the Grim rushing the serpent's head in its jaws and in that moment for the first time they heard a scream coming from behind them. All startled from the display that and consumed them turned their heads to look at the still roiling storm of magic as for a moment from within it Harry screamed. Unable to take anymore Hermione stood to her feet in a burst of energy. "Enough we have to stop this. Harry is hurting, whatever this is that is going on it is bringing him harm!" Sitting beside her Mrs. Tonks simply grabbed her wrist with an iron grip and pulled her down back into her seat.
The outcast member of the Black family fixed the girl with a stern imperious look that cowed Hermione's concern for Harry's well being back into her. "We shall do nothing. This is a matter of family magics and it will run its course. Family magics go back thousands of years and if you attempt to stand against it you shall fare no better than attempting to turn back a hurricane. There is nothing you or even any of us can do but sit and wait." She turned her head slightly to look at where Harry was still sitting hidden by the magic then turned her head back to the avatars of family magic. "No matter how much we might desire..." She murmured so quietly under her breath that not even Hermione sitting next to her heard her although across the table Mrs. Malfoy arched an eyebrow as she watched her sister sitting across from her.
By now with the distraction of Hermione over and Harry silent once more they all turned back to look at the display of the raw primal power of family magics once more to see the grphon sitting proudly one one side while the Grim claimed its prize by devouring the snake. The grphon seemed content to watch though its golden gaze was on the Grim and it spared none of them so much as a glance. The grim continued to devour the snake bite by bite by bite by bite. Its jaws rended the defeated serpent still formed of ethereal magic given form as it lay on the floor as the Grim consumed it bite by bite. No one noticed it given that all eyes were on the Grim as it consumed its meal but Dumbledore's eyes had widened in shock and surprise and his mouth hung open as if he was about to say something yet nothing could come to him as he was unable to look away from the sight.
Minutes passed as the Grim ate up the entirety of the snake, it seemed impossible given how much larger the serpent had seemed and it was true that the Grim seemed to grow slightly by the time it had consumed its meal but it continued to eat and devour its prey. When it was finally done the Grim let loose a howl of victory that sent a fresh chill down the spines of everyone in the room. It seemed as if it was over and everyone was about to breath a sigh of relief that it had finished when the gryphon stood and raked its claws across the floor drawing sparks as it gouged the stone.
The Grim likewise stood once more and briefly growled at the gryphon. Then the two magical avatars launched themselves at one another to the shock of all. Minutes before these things that were entities of house magics of both the houses Potter and Black had fought together against the serpent and emerged victorious, and yet now they fought one another, everyone that sat at that table even prideful Draco grew pale at what was passing through their minds as the two house magics fought one another anew now on opposite sides.
The grphon though it seemed larger quickly became the apparent weaker challenger as the slightly smaller though still huge Grim managed to avoid its claws only to respond with bites from its powerful jaws and its own less impressive but still deadly claws. For half a minute the two beasts fought before finally it came to a halt when the Grim managed to get its jaws around the gryphon's neck and both beasts froze. Everyone's breath froze as well, they had seen the Grim minutes before crush the serpent's head in its jaws, were they about to see a similar fate befall the avatar of the house potter magics?
It seemed not as after agonizingly long seconds the Grim released its grip on the gryphon's neck and took a step back. Sitting with regal bearing the Grim watched as the gryphon bowed before it. Both creatures gleamed with blood formed from red ethereal magic that clung to their bodies from where they had brought harm to each other and before that the serpent to them, but the battle was over now and the Grim gave a howl of victory that was taken up by a loud screech by the gryphon as well. Then the two entities bowed to one another as one, and walked back one on either side of the table and one after the other disappeared into the magical storm that had never stopped swirling around where Harry sat.
Immediately the roiling storm of black and grey magic calmed around him until second by second it shrank and faded until at last the chair and the young man that sat in it were revealed once more. But as he became visible for the first time in many long minutes a sharp gasp emerged from several around the table before a moment later in the silence that hung in the room for a few long seconds before Dumbledore's voice could be heard to say a quiet. "Oh dear..."