"Okay," Harry said loudly, automatically taking charge of the interrogation simply because he was the one who Stunned Malfoy, and for no other reason, "We should tie his hands. When we wake him up he'll probably be a bit violent because he's a prick, then we need to keep him at spearpoint and wandpoint at all times. And we give him the good cop/bad cop routine until he cracks and spills something."
"What's the good cop/bad cop routine?" Ron asked, perplexed.
"I think Ernie should be good cop, because he's the only non- Gryffindor in the room," Harry continued, ignoring Ron, "but who wants to be bad cop?"
Harry looked at the potential candidates. Dean seemed to be utterly absorbed in his task as a door guard, Ernie was already indisposed, Hermione didn't have it in her to be mean, not even to Lucius Malfoy, and Ron was too self-conscious to be an effective bad cop. Harry sighed. "Fine, I'll be bad cop. Somebody tie him up and search his pockets." Ernie pulled a long bit of string out of his pocket and wrapped it around each of Malfoy's hands several times before tying it off with a ridiculously complicated knot. Then he patted Malfoy down in a professional manner, coming up with nothing. "Now, Hermione and Ron, hold him at wand point, and I'll take the spear. When we wake him up, Ern, you need to expound to him the immediate advantages of telling us the truth. When he doesn't, I'm gonna poke him about with this thing to hurt and scare him, then I'm gonna drown him a bit in the bath." At this Harry turned on the bath's faucet, and he watched it magically fill up far faster than it should have done with just one small tap. "Then you're gonna ask him again, but before he answers I'm gonna slap him around and ask him again. Then you're gonna to tell me to be nice, and you're going to remind him that answering truthfully is the fastest way to stop this. And we go from there."
"It's a good plan." Ernie said half-aloud, nodding. "Get in position."
Hermione pointed her wand at Malfoy and said, "Enervate."
Malfoy regained consciousness fairly slowly, then started kicking and thrashing about on the floor, trying to break his bonds. He looked around, incensed at how he was tied up, and noticed he had three weapons pointed at him. He gave up struggling and sighed.
"Dear me, the stigma of being caught by people who are nearly all of impure blood. Let me go, foolish children, and I will spare your lives."
Harry reacted quickly, smashing him in the mouth with the spearbutt. Malfoy's head jerked back, then resettled to its normal position. Malfoy glared at Harry, but postponed his next insult so he could first run his tongue over his lips, tasting for blood.
"Mr. Malfoy," Ernie began smarmily, "it is of my understanding that you and a somewhat meagre band of minor miscreants have decided to play a practical joke on this school by bringing in the least civilised citizens of the Forbidden Forest to roam the school corridors. I was hoping maybe you could help me and help yourself by telling me who sent you."
Malfoy sat up and looked around. "So, Potter, Granger and Weasley ganged up on me from behind. How very noble of you."
"I assure you, sir, that it is in everyone's best interests that you tell us now." Ernie ploughed on. "If you decide to delay telling us for five minutes, while we lose five minutes, you might just lose five fingers. And if you don't tell us, you might just lose your life."
Malfoy looked pained. "Child, on several occasions Lord Voldemort performed the Cruciatus Curse on me when I failed him. Do you really think a spear has anything on the Cruciatus Curse? Ask Harry, he knows what it's like."
Harry plunged the spear into Malfoy's leg, savoured his shout of pain, twisted it, and pulled it out. "You will learn some respect for your captors," Harry purred, injecting fake sadism into his voice by the bucketload, "and you will also tell him what he wants to know."
"Sod off." Malfoy growled.
Harry stepped on the wound, leaning on it. Malfoy grunted, but kept his shouting in. Harry dropped the spear, grabbed the hem of his robes, picked him up, and threw him facedown on the edge of the bath.
"Guess what's coming next." Harry whispered in his ear. "You want to tell me now and save all that spluttering you're going to do?"
"No." Malfoy said coldly. So Harry dunked him, holding his face under, while he struggled against his bonds. Harry held him under for quite a time, really testing how well Malfoy could hold his breath. Finally he lifted his head back over the water.
"Tell us who sent you and what you're here to do." Ernie advised him. "Otherwise I gotta let psycho-boy here have some more fun with you."
"I'm not going to tell you." Malfoy repeated.
"Come on." Ernie said. "This is clearly Voldemort's doings. Death Eaters running around in traditional Death Eater regalia, going after a long-standing Death Eater foe? Just admit that much. You are under the command of Lord Voldemort."
"I admit nothing." Malfoy sulked, so Harry held him under again. This time he held him under even longer than he did before. He waited until Malfoy's thrashing began losing some of its enthusiasm before bringing him back up. And after he did, he slammed Malfoy's face against the rim of the bathtub for good measure. Coughing and choking, and also spitting out a tooth, Malfoy was not in good shape.
"Please start talking." pleaded Ernie. "Otherwise I gotta let Harry kill you, and then he gloats for hours afterwards and nobody's happy. Tell us what you know."
"My friends... will come get me." he gasped.
"No they won't." Ernie assured him. "They barely know you, you're just another extraneous cog in a broken-down machine, even if they knew you were missing they wouldn't give a damn about you."
"My friends will come get me," he repeated, "and then you will be begging for my mercy."
"Keep telling yourself what you want to hear, whack job." Harry told him unkindly before thrusting his head underwater again. This time he held the man under even longer than before. The seconds passed slowly, Lucius thrashing about. His jerks slowed down, and began convulsions instead. At last Harry let him up.
"Look, Lucius, I'm bored with this game now." Harry said uncaringly, turning him around and letting him lean on the side of the bath. "Either you talk right now, and we let you live, or I will kill you with this primitive tool and let your rapidly cooling corpse bleed all over the floor. I'm not joking; it's an absolutely final ultimatum." Harry held the spearpoint on Malfoy's neck at a downward angle, leering into his face.
"You'll find out the hard way who sent me when they kill you." Malfoy said pleasantly. Harry leaned very slightly, drawing blood. Malfoy choked slightly and shook. "Look at it from my perspective Harry. Even assuming that you would let me live if I told you anything, Voldemort would kill me himself when he found out that I did."
Harry turned, grinning, to the others. "You see? Perseverance pays off. I got him to admit he's working for Voldemort."
Malfoy's eyes bulged as he realised this. He lashed out with his good leg at Harry's forward leg, disrupting Harry's balance. An automatic human reaction was to balance himself by leaning on the pole he was holding, accidentally driving the spearpoint right through Malfoy's entire neck. Malfoy was killed almost instantly. Blood steadily dripped off the spearpoint onto the white tile floor. "Damn it." Harry muttered in annoyance. He dropped the spearshaft, and Malfoy slowly toppled over to the side. Everyone stared horrified at the body.
Ernie broke the ice. "At least we can be pretty sure who's behind all this." he said.
Suddenly there were two pairs of footsteps outside the door. "I swear I heard something." a voice reiterated. There was growling from the throats of troglodytes in the background.
"Fine, check it out." another voice capitulated.
"Hey, it's locked." the first voice said, jiggling the doorknob.
"Then jinx it open, Nott, you slow bastard!" the second voice scorned. Harry recognised it as Macnair's voice.