Minerva McGonagall knew the exact moment when it started, because she hadn't seen Draco Malfoy smile like that in years. She was used to smirks, yes, and the ubiquitous sneer, but a true smile, one that lit up his face and tugged at the corners of his eyes was something she wasn't sure she would see again inside these walls.
It started out slowly, as these things often do, and not very well at that. It was a sneaking glance in the hallways or a mumbled "Morning," or "Afternoon," or "Evening," if they ran into each other outside of class.
There were the stares in Transfiguration that had her rapping her wand and clearing her throat more than once in the hopes that two of her brightest pupils would pay some modicum of attention to her lecture. She often had to hide a smile behind her hand at the shy blushes and nervous fidgeting that would happen when they were paired together, because for all of their experience fighting a Dark Lord and saving the wizarding world, Hermione Granger and Draco Malfoy were very much teenagers inexperienced in love.
It was uncertain, for a while, when Hermione was still with Ron; a time when the stares were icy cold instead of wondering warmth and plates were hardly touched, faces drawn and magic dimmed.
But time passed, and as the first snows fell on the grounds of Hogwarts, it appeared that all was indeed well again between the pair. They often stopped to talk between classes, eyes flashing and hands flying as they discussed one topic or other. Sometimes hexes were traded as easily as words when they became riled up, the air veritably crackling with magic and chests heaving as they fumed at each other. She often thought that Draco provoked her intentionally purely for his own entertainment; a decidedly wicked twinkle would light his eyes as he sat back to watch her, hair flying and face flushed as she strove to prove her point. He derived, certainly, a different entertainment from it than that of his younger years.
Minerva never could understand how Hermione thought that Ron, whose interests remained in the sphere of Quidditch and the components of his next meal, could possibly entertain her. It is just as likely that she didn't think. War has a way of making hasty lovers.
One day during a meeting Horace confessed that he had partnered them on a lengthy potions project as a means of hurrying their relationship along, a confession that led to an extensive and complex system of betting between staff members as to the date and time they would come together, and the number of Howlers that would result because of it.
As a consequence of Horace's pairing Minerva often observed them together in the library, pouring over some text the size of Hagrid's torso, late into the evening. Draco would lean closer to examine the text, sliding an arm across the back of Hermione's chair, and she would smile softly at him as the waning light cast deep shadows across both their faces. Minerva chuckled to herself when she noticed that whatever book they were reading would always be pulled more towards Hermione's side. She doubted that Draco ever complained.
With the New Year came casual touches: a firm hand on the small of a back or a comforting palm across the shoulder. There were teasing jostles of elbows and playful nudges; secret smiles as private jokes were exchanged.
She regularly marveled at how well they knew one another. It became a habit for them to come to breakfast early, with no one to observe them eating together other than teachers and bleary-eyed Ravenclaws.
They would sit side-by-side, sharing a newspaper between them as Hermione passed Draco the coffee carafe and he slid her the pitcher of pumpkin juice. She knew that he took his coffee with two sugars; he knew that the only kind of jam she liked was raspberry.
Minerva could tell when one of them must have had a bad day; expressions were softer, touches lingered, voices remained subdued with soothing platitudes.
They often seemed to communicate without words. Draco would say something that made Hermione's eyes flash, he would quirk his eyebrows into the appropriate response, and they would chuckle together as though they knew exactly what the other meant.
It left Minerva rather baffled.
She knew the exact moment when she realized that Draco Malfoy was in love with Hermione Granger, because Madame Valens, the new Care of Magical Creatures professor, came barreling into the staff room and shoved a roll of parchment under her nose. It was an essay that Draco had written, outlining the reasons why house elves should be granted sovereignty. She managed not to faint, but it was a near thing.
It was exam time which brought it all to light, however. Though Hermione had mellowed considerably throughout the year, exams were still something she took quite seriously. The signs began at the start of May, when content in classes began to dwindle and the opportunity for revision grew.
Fluttering hands, unmanageably tall stacks of books, and dark circles under eyes began to manifest themselves.
Minerva McGonagall knew the exact moment when she realized that Draco Malfoy and Hermione Granger were meant for each other. She was passing through a corridor, admiring the mild weather and reveling in the fresh breeze moving through the castle when she noticed two familiar figures standing at the edge of the courtyard.
The brown-haired woman was twisting her hands as she looked up into the face of the blond man, a look of distress written across her features. He smiled lightly at her, a smile that lifted the corners of his mouth but failed to reach his eyes. Minerva knew that look. It was a look of uncertainty, of knowing that you are faced with questions without answers.
And with that look Minerva understood that it was not the threat of upcoming exams that had her best student's nerves shredded to pieces.
It was the future.
Across the yard Draco cupped a hand around Hermione's face, thumb moving to erase the tears that had made their way down her cheeks.
"Come here," he said, drawing her into his arms. She leaned into him as if they'd done this hundreds of times before, sighing into his chest as her eyes closed and her arms came to circle tight around his waist.
Minerva couldn't hear what he was saying as he pressed his face into her hair, but Hermione's body began to relax against him at his words.
They stood like that for a time before he smirked suddenly and whispered in her ear, and Hermione pulled away with a laugh as she swatted his arm. Draco's smile was back to its eye-tugging fullness as he drew her near again, placing a soft kiss on her forehead and fixing his arm around the curve of her waist.
His eyes were alight with something warm that Minerva had never seen before, and the answering light in Hermione's eyes said more than enough as to the state of their feelings for each other.
Because Minerva knew those looks. They were ones of certainty.
And as she watched the two walk down towards the lake arm in arm, Professor McGonagall, pleased for the pair, turned down the corridor to collect her winnings.