Disclaimer: All rights and quotes are JKR's. The dirty stuff is our idea :D bwahaha. But I think I died on the inside just writing this.
It was easy, once out of the party, to pull his Invisibility Cloak out of his pocket and throw it over himself, for the corridor was quite deserted. What was more difficult was finding Snape and Malfoy. Harry ran down the corridor, the noise of his feet masked by the music and loud talk still issuing from Slughorn's office behind him. Perhaps Snape had taken Malfoy to his office in the dungeons... or perhaps he was escorting him back to the Slytherin common room... Harry pressed his ear against door after door as he dashed down the corridor until, with a great jolt of excitement, he crouched down to the keyhole of the last classroom in the corridor and heard voices.
"...cannot afford mistakes, Draco, because if you are expelled-"
"I didn't want anything to do with this, all right?"
"I hope you are not telling the truth. Do as I say or I will have you expelled! Then you will never finish the Lord's orders! There are already suspicions of what we are doing."
"Who suspects us?" sneered Malfoy. "For the last time, I don't want to do this! You know I'm not gay! Oh, don't look at me like that!"
There was a pause and then Snape said quietly, "Ah...Aunt Bellatrix has been teaching you Occlumency, I see. What thoughts are you trying to conceal from your master, Draco?"
"I'm not trying to conceal anything from him, I just don't want you butting in!"
Harry pressed his hear still more closely against the keyhole... What had happened to make Malfoy speak to Snape like this - Snape, toward whom he had always shown respect, even liking?
"So that is why you have been avoiding me this term? You have feared the things I enjoy so much?"
"Fine. Just get it over with," said Malfoy, a faint bitterness in his voice.
"Listen to me," said Snape, his voice so low now that Harry had to push his ear very hard against the keyhole to hear. "You know what I am like. I have never favored any other students such as you."
Malfoy laughed coldly. "Sure. You're so desperate you would even do Potter!" There was a moment of tense silence. And then, ever so faintly, Harry heard an odd sound...but he shook the thought away. Peering into the keyhole, he clamped his hand over his mouth at what he saw. Snape was snogging Malfoy! Malfoy... and Snape? Reluctantly intrigued, Harry stared into the keyhole again. His eyes widened with surprise and horror as he saw Snapes tongue licked the inside of Draco's mouth. He tried his best not to utter a gasp. He saw Malfoy shove Snape off him with all his feminine strength.
"I hate that!" Malfoy jerked his head away, but there was a redness to his cheeks. Snape merely smirked. And then Harry saw a very odd sight indeed - Snape slid his arms around Malfoy ever so lovingly. Draco's cheeks flushed an ever deeper shade of red. "Stop acting like you love me... we both know you just need a way to get off." Snape's lips curled into a frown.
"That's not what you said last time." Malfoy's eyes widened, and an expression of triumph came over Snape's face. Again there was rustling of robes, and Snape was tenderly kissing his lover's neck. Harry felt his own cheeks flush a deep red, and shook off the thought. He felt his heart hammering inside his chest... was this legal? Dumbledore can't know about...
But Malfoy was leaning into the embrace, and Harry felt the sudden urge to have nacho chips and beer and American football, to be manly. Yet he couldn't bear to tear himself away from the sight of Malfoy and Snape. It intrigued him and even... turned him on? No way, he silently scolded himself. I like Ginny! He was blushing and so was Malfoy as Snape unbuttoned the top button of his robes.
"I don't know, Severus," whispered Draco. But before he could protest again Snape had pulled off his school sweater, and was eagerly unbuttoning his shirt. He had pushed Draco against the table and was kissing him forcefully. His hips jumped, but Malfoy let out a small cry, muffled into Snape's mouth. He tried feebly to push him off, but Snape lifted his arms above his head. Harry began to panic once again, he can't just let Malfoy get... raped. But all thoughts of coming to his rescue and calling for help vanished as Malfoy sighed "More..."