Harry had trouble sleeping that night. He'd rolled over half a dozen times to find a comfortable position. When he'd finally given up, he decided a walk might tire him out, enough to get a few hours sleep in at least. He silently unearthed his invisibility cloak from his trunk and made his way through the Gryffindor common room. No one else was awake; Harry breathed a sigh of relief. It would have looked very strange if the portrait had opened and no one come in. He was also thankful that the fat lady was sound asleep, so she too wouldn't know of someone leaving the tower after hours.
He had no clue how long he'd been walking, but it must have been some time, as he now found himself standing directly in front of the door to the dungeons. The smell of mold and dampness wafted from behind the solid oak barrier. His first thought had been to return to the common room, where he would somehow manage to wake the fat lady just enough to get her to open without realizing what time it was. Then, another thought occurred to him. Why not explore the dungeons? He'd only been allowed down there for potions, and that one time Draco had believed he and Ron were really Crabbe and Goyle, otherwise that was Slytherine territory. They alone knew the layout of the castle's bowels. But, who was to say Gryffindors couldn't explore the dungeons as well? A smirk playing on his lips, Harry opened the door as quietly as he could, though each groan and crack echoed off of the stone walls.
The dungeons seemed blacker than black, if that was even possible. No torches lit the hallways, but Harry dared not light his wand for fear of being caught. He gave himself time to allow his eyes to adjust, and slowly, he could make out the faint outline of the walls and floor. It seemed that the moss that grew along the corridors had a purpose other than giving off a tangy smell. The moss itself was glowing, very faintly, enough to guide Harry without tripping too often. Thankfully, he'd worn his slippers, which prevented his occasional trips from making too much noise.
He opened several doors along the first corridor, silently fearing that one of them would lead to a dorm room where he would be attacked by an entire gang of Slytherines. He'd been lucky, though. So far all he'd found was a broom closet, two empty classrooms, and the Slytherine Common Room, currently empty. He reached yet another door and held his breath, pushing the wooden door open slowly. This door, unlike the others, slid open without the slightest bit of noise, and Harry understood why immediately. This was one of the boy's bathrooms, and with students needing to use chamber pots in the middle of the night, this door got the most use. It was probably kept well oiled to ensure that it wouldn't wake up any of the other students.
The room itself was very ornately designed. The floors and walls were tiled with brilliant greens and sparkling silvers, the colors of Slytherine house. It was at that moment Harry realized he had to go, and wouldn't be able to hold it all the way up to the bathroom on the second floor. He bit his lip for a moment and sighed, carefully stepping towards one of the stalls. The door shut silently behind him, and Harry slid the latch closed achingly slow to avoid even the slightest noise. He had just been about to undo his trousers when he heard a muffled noise coming from the next stall. He froze in horror. Was someone else in the room? Of course, it was a bathroom after all, and he'd been lucky not to walk headfirst into a Slytherine as he entered. Hopefully this student hadn't heard him. Harry waited, his breath held painfully in his chest. At another muffled sound, he began to breathe again, filling his aching lungs.