Dean Thomas liked to watch people. Not only in the voyeuristic sense of the word; he liked watching people because the insights he gets from watching make him privy to their secrets.

He spent so much of his time watching people that sometimes he felt oddly distanced from whatever is going on around him, as if he were watching a play unfold around him. Perhaps that is why, when Ginny Weasley broke up with him, he'd simply accepted it, instead of trying to win her back. He didn't even demand an explanation from her, even though he still felt bitter about it.

He feels he knows most of what is going on around Hogwarts, perhaps even knows the intrinsic characters of most of the people in Hogwarts.

That is why late one night, when he is on his way back from a midnight detention, he is so surprised by what he sees.

Ginny Weasley and Draco Malfoy, in the Charms classroom. He is on his back on one of the desks, and she is riding him, skirt hitched up as far as it would go, knickers lost on the floor somewhere.

He's always thought that him, of all people, could pick up on tiny nuances in the behavior of people around him, be able to tell when a relationship changed.

There were, he told himself, three possibilities. Perhaps he hadn't noticed them because they were simply using one another, and no feelings were involved so there would be no change in their behavior. Or maybe they had been together for so long that there were no changes to be seen, for when he first knew them it was already there, affecting their actions. The last, and most unlikely, was that their relationship had slowly, subtly, changed, so infinitesimally slow that even Dean couldn't tell. But that implied that what they had was there to stay, that it was a long-term thing. Dean dismissed it.

He watches them especially closely in the following days. He notices that Ginny is always glancing at Malfoy, and realizes that even when they were together, she'd done this, and he'd just thought it was natural wariness of an enemy. He sees that Malfoy's owl sometimes delivers letters to her during breakfast at the Great Hall, and that she flushed a bright, pleased red whenever she gets one.

Malfoy, though, is harder for Dean to puzzle out. He sees that Malfoy often looks across at Ginny, but his face is so blank that Dean has trouble discerning his expression. Once Dean had the sudden, surprising thought that perhaps when he looks at her Draco does not really see the red-haired girl chatting delightedly with her friends, or munching on her rashers, instead seeing past the mundane things to the essence of Ginny Weasley, is instead seeing the real her. But he tells himself that it cannot be so, and continues watching.

He supposed that he realized what exactly it was during a Detention, about a month later. Malfoy, Ginny, and Dean happened to be in the same Detention, and he secretly rejoiced at being privy yet again to their hidden interactions.

Malfoy was levitating Potion bottles across the classroom, wand work impeccable as always, sending the bottles into their respective places on the shelves with nary a clink, not even bumping the other bottles. Ginny was labeling potions in a corner, and Dean was scrubbing cauldrons.

Terry Boot was supervising them that night, and when he went over to Ginny's corner and talked to her, their hushed voices the only sound in the room, Dean sees Malfoy glance up. When Terry Boot put his hand on Ginny's arm, trying to persuade her, Draco accidentally sent a bottle smashing to the shelf, glass splintering to the floor among the droplets of potion. Dean, watching him, saw the slightest twitch in his eyelid, something he'd always noticed whenever Malfoy was pissed enough to lose control.

All of them looked up, startled. Malfoy flushed, apologized sullenly, and cleaned it up. Ginny gave him an inscrutable look before returning to her task, dismissing Boot with an irritated wave of her hand.

And then it all came together for Dean. It had been there for a long time, true, but he realized that the way they interacted belied a hidden understanding of one another that only the third possibility allowed room for. And now he didn't mind Ginny leaving him.