They were outside in a large courtyard surrounded on three sides by tall, roughly dressed stone walls. Behind them, the castle rose up to a dizzying height before giving way to twilight sky. Hermione followed Minerva into the patch of wild grass surrounding an outcropping of granite that covered about a third of courtyard's surface area. On the surface of the flat granite, loops and whorls chased one another endlessly, smooth and serpentine; Hermione could not see the end of a single line. Granite boulders formed darkened lumps at even distances on a circle. At the center of the circle, where the twisted patterns converged was a rough altar, a large undressed block of marble. It clearly belonged there, as weather-worn and ancient as the rest of the stone, but Hermione knew there was no marble quarried in the British Isles.
A static charge ran through her fur, as palpable as a hand, and left her ruff standing upright in its wake. The magic here hung in the air like moisture on a humid day, and Hermione panted her discomfort.
Minerva grinned at her, her eyes green fairy lights in the moon's subtle glow. "The magic here is quite wild, my dear; neither human nor beast nor anything familiar. It will feel alien and uncomfortable to you for a while, yet."
Hermione changed form - at the very least she could ask questions as a human - and perched next to Minerva on one of the stones that formed the megalith's outer circle.
"What is this place, Minerva? I've never felt anything like it."
"This is the magical heart of Hogwarts - the Fireach Cridhe, the Moor's Heart. I'm sure you've heard about megaliths and ley lines and ancient ritual sites." Hermione nodded. Megalithic ritual sites were often placed on points where ley lines, lines of natural magical energy produced by living things, intersected. This was a particularly powerful example of such a place.
"This ritual site is a bit special. It was the reason that the founders chose this spot for the castle, of course, but since its nascence as a site of worship, its caretakers have been nurturing this wellspring with bits of their power and knowledge. Not just humans either - centaurs and unicorns have also taken advantage of this site's particular qualities and nurtured it as well." Minerva pointed to a dark archway on the wall opposite the castle.
"The leaders of their Dark Forest colonies have access through that gate much as I do."
Minerva pushed herself off the stone and walked a few steps closer to the altar. The hair loosed from her braid began to stand on end, and Hermione could see a shiver pass over her pale skin. Minerva didn't seem discomfited, though. The magic in the courtyard seemed to energize and revitalize the older witch, sinking into her pores and causing her to luminesce with an unearthly internal light. Hermione would never have thought of Minerva McGonagall as untamed in any context, rather the opposite, actually, but at this moment she was fierce and free in a way that Hermione thought beautiful.
"This place has long been one of the most powerful magical places in all of Europe. Guardianship confers powerful benefits on two members of each of the groups pledged to protect it - humans, unicorns, and centaurs. Increased power reserves, extended youth and expedited healing are the bigs ones, but there are some gifts that are more particular to the individual." Hermione was sure she was gaping. Her friend and mentor was lit up like the moon herself, her eyes lidded much like they had been when Hermione had been scratching behind her ears, recharged and centered, and as visibly powerful as Hermione had ever seen a magic user. Hermione just felt itchy.
"After the Battle of Hogwarts, the Heart had changed. It..." She paused and Hermione could see her shudder again. "Seeing is probably better for believing."
A ripple of wind shifted the grass around them, and all of a sudden it seemed like every scrap of light in the courtyard had coalesced into the vague shape of a human standing next to the altar. Its outlines blurred, and then it was a centaur, then briefly a unicorn, before it settled back into its vaguely human shape.
"Soft-pawed feline/jagged toothed hunter/changer of shapes, I greet you," it said in a voice that was almost indistinguishable from the soft summer breeze that rustled the trees outside the courtyard walls. Hermione's jaw dropped.
"Hermione, this is the Heart of the Moor." Minerva moved to where the girl was sitting, laid one comforting hand on her shoulder and used the other to shut the young woman's mouth with a 'click'. The older woman was amused at the normally sharp Hermione's less than quicksilver response.
The Heart pulsed, a happy sort of flare that increased its brilliance by an order of magnitude, then dimmed again. "The little fox with the leaping blue mind - Hermione Granger - I'm glad you have returned. Did my gift please you?" Its shape contracted expectantly, waiting for a response. Hermione was dumbfounded. Gift?
"Has she been damaged, Tabby? I felt her return to the castle, and her mind seemed in order, but she does not speak."
Hermione found her voice. "My apologies, just a bit shocked." She shook herself. "A gift, you say? I don't..."
"Your extra form. The wolf. It was not supposed to manifest until you had come back to the Tabby for more of your learning, but it seems you undertook many studies on your own." The Heart dropped its chin and its outline wavered in...embarrassment, perhaps. Hermione's jaw dropped again. Minerva's eyes were dancing mirthfully, her lips pressed together in an effort to contain her laughter.
"I apologize if you were surprised." It seemed to contract into itself even more. "Sentience is new to me and I'm having trouble adjusting to interaction on a more immediate basis. I wish to give gifts that my protectors will appreciate, and that are relevant to their expertise, but I find I am quite clumsy in my attempts." The Heart appeared frustrated. "You would think that thousands of years of existence as a semi-aware magical intelligence would at least afford me some ease interacting with sentient beings, but the Tabby tells me I have the social graces of a room full of third years."
Minerva bit back a laugh and Hermione fought the urge to elbow the older woman in the ribs. "Its just the incongruity of it all, I apologize," the older witch explained to her young, flabbergasted apprentice. Softening, she said: "I know this is an odd situation." Her green eyes flickered to Hermione's face. "But we will work on your feeling detached from the castle and forest. I am sure the people who set up the wards had no inkling that Albus would meddle so with the nature of this place. I wonder all the time what plan he had hatched to integrate your sentient self more fully into the goings on of the castle and its environs." The Heart solidified a bit at Minerva's reassurances; Hermione goggled at the mention of Dumbledore. "And anyway, you have Hermione to talk to you now, as well."
Hermione was aghast. "Minerva, I'm just a transfiguration apprentice. I'm not a guardian of the most powerful magical site in Britain." Her eyes looked wild and Minerva could see her begin to pant.
"Hermione. Hermione, take deep breaths." Minerva took the girl in her arms, hoping the touch would ground her rather than embarrass her.
"Little fox, it wasn't supposed to be this way." The Heart sounded sad, its voice desolate. "When the mirthful phoenix left us, it was the watchful serpent that was to take his place as guardian, but he had been...corrupted, and had too many masters. And then, in the battle that gave me awareness, he died."
The Heart stepped closer to where Hermione stood in Minerva's arms and placed its translucent hand on her forehead. Hermione cringed away, uncertain about accepting the touch of a creature made entirely of magic; Minerva held her tighter.
For Hermione, it was as if time had stopped. She could feel the Heart, feel its awareness stretching almost endlessly in every direction from where it stood, racing through the granite of the castle and along the tendrils of the root systems of the old growth in the Forbidden Forest. She sould feel its joyousness and delight now that it was awake, though she suspected it was hard to be very solemn with a thousand years worth of mischievous witch and wizard children traipsing over one's bones. Its sense of completeness sank into her being, as much a comfort as the solid presence of Minerva behind her. It was glad she was here, and hoped she would stay. Its strength felt like the strength of her own magic, and its wisdom felt like the knowledge of her own mind.
It spoke to her. "Be at ease, witch-child. I know your worries, and all will be resolved, and now that you are home, you will know the peace of the truly contented soon." Its tone became more serious.
"Will you remain here with us to weather the coming storm? Hogwarts will need you in order to remain unbroken, and Minerva will need you to temper her bravery and safeguard her heart." Hermione's head spun; she wished to stay. Truly, she knew she needed to stay, but was what the Heart spoke of even possible? Hermione had never dared to dream such a thing.
"Love has many faces, little fox. What form yours takes is between you and the Tabby. But I am able to pierce the fog of your confusions and uncertainties, somewhat, and your feelings for her run very deep. The Tabby feels much the same, but you need not take my word for it. I give you gifts, Hermione Granger, little fox, to aid you on your path. Your eyes will never be fooled by illusion. When in animal shapes, you and the Tabby will be able to converse as clearly as I speak to you now. And finally, you will always know what is in Minerva's heart."
The glowing hand withdrew from Hermione's head, and all went dark.