Cold, dead eyes watched keenly the dance of spells and feet, as Harry Potter fled from the dungeons, through the dungeons, deep into the depths of the castle, and through a secret door winding up blinking at the light of the first floor, near the dancing hall. The deathless had a curious freedom - the ability to pass through walls, to look even at those in particular places of hiding. And, as a Slytherin, the Bloody Baron knew of many secrets, including how to be not quite visible, despite being an inherently glowing entity. A sliver of moonlight, a peek of an eye (the rest of his face inside an object), and he had the names he sought.
As out of a nightmare, he glided through the dark dungeons of Hogwarts, where sleeping Slytherins lie.
In the dark of the night, only one candle lay burning. The Bloody Baron entered without announcing himself, knowing that the tall, darkclad man would notice his presence anyway... eventually. The Bloody Baron's lips curled into a bloodless smile as Professor Snape stiffened, acknowledging his presence.
The Baron said only one word, "Flint." He would hold his knowledge of the young scamp tightly, as was a Slytherin's wont. If the Head of Slytherin House wanted to learn more about the boy, well, he would have to look himself. Or bestir himself to ask for it. After all, Slytherins did not share their secrets for free - and knowledge was the greatest secret of all.
[a/n: What, you thought Snape was giving Potter detentions for fun? He has better things to do with his time! Leave a review.]