He stopped just outside the bathroom door. The castle was silent, as always, but he wanted to be certain nobody could see him. Quietly as possible, he creaked the door ajar and slipped inside. He imagined the bathroom would be the best place because of it's wide, sloping pipes running around the school. He sank to his knees as he neared a small sink set into a pole, reaching the ceiling. Now that he was eye level with it, he could see his reflection in the copper tap. Here was the place. Raising his wand, he carved a miniature serpent into the side of it. When the day came, his heir would know exactly who made this, all because of this small symbol.
He starred at the snake for a moment, and imagined he could see it wriggling around by the trick of the light dancing across it. "Open," Salazar hissed in Parseltongue. Immediately, a large gap began to open, forming a long chute. He took a gulp, and jumped. The drop was longer than he had expected, nevertheless, he landed softly on the moss-strewn floor. "Lumos," he whispered, and his wand tip ignited.
Looking around, Salazar realized exactly where he was. He had landed on the bottommost floor, the lowest dungeon. This was much more than the average dungeon, however. The faded stone walls dripped with water and mildew, and the floor was covered with puddles and moss. Frantic scurrying noises told him there was a family of mice nearby. Salazar cautiously crept forward, holding his wand high above him to light the way. Every footstep made a loud slapping noise in the small amount of water.
Finally he arrived in a huge, open space. Parts of the high ceiling had caved in, leaving piles of rocks and debris scattered around the room. Here was the perfect place. Usually, when performing magic, Salazar would have used his wand. Now, however, he raised his hand. He had taught himself this ancient magic, and was quite good at it. Tensing his fingertips, Salazar directed his hand at a pile of rocks. They instantly flew up and landed in random spots along the back wall. Slowly, he carved out a hole in the center of the wall. he looked up to the wall, but instead was now looking at his own features. He had carved an enormous replica of his face into the wall. He had left his mouth open in the statue. Now, he called into the silence,"Come," in the strange, hissing language. At his command, the long shadow of his snake slithered into the room. "Go," he commanded. The serpent coiled itself up and crawled into the statue's mouth. It vanished into the darkness of it's depths. Now Salazar was certain his Basilisk would remain there dormant for centuries, until his rightful heir came to unleash it upon his school and wipe out the Muggle-borns.
His work finished, Salazar turned to leave. He whipped around and walked quickly down the long aisle he had come from. Then, he stuck out both hands on either side of him. Bright, silvery sparks shot from his palms. He concentrated hard. Large, stony-grey statues of serpents burst forth from the ground. They filled the chamber with eerie sounds and made the floor tremble. Once in position, long, spiked fangs protruded from their skulls, and suddenly as it started, it stopped.
He closed his eyes. Around him, shaky waves in the still water began to form. They rose up like a miniature tsunami, and encircled Salazar. They made a cocoon around him, drenching him and suffocating him. Then the waves burst apart, slopping over the aisle and swaying back into place. But Salazar had vanished.
The Chamber of Secrets had been opened.