I have no words.
Luffy was slammed roughly face-down on the desk, knocking luxurious feather quills and ink wells to the side. He winced slightly and twisted his head around to look up at Lockhart.
"Professor," he groaned, biting his lip. "This isn't what you said detention would be!"
"This is your punishment, my boy," Lockhart smiled at him, caressing his jawline with a long, thin finger.
"I don't know wha-"
"Shh, you'll learn to like it," Lockhart insisted, still with that winning smile of his. The hand which wasn't pinning Luffy down moved to his waist-band, tugging it down and smacking Luffy roughly on his small twelve-year-old behind when he made a noise of protest. Luffy squirmed uncomfortably.
"Wait, isn't this bad? What if someone sees?" He tried to pull his pants back up but Lockhart slapped his hands away.
"Are you that worried?" he asked, squeezing a pert ass-cheek. Luffy shut his eyes and pressed his forehead into the desk. His face and neck burned with embarrassment and he tried to wiggle away again. Lockhart whipped out his wand and cast a spell which bound Luffy to the desk. The boy slumped, giving up on trying to break the bonds. "Much better," Lockhart purred.
"I don't understand," Luffy whined, pressing his knees together. Lockhart wasn't put off by his shyness and spread the rubber asscheeks apart to get a look at the tight, twelve-year-old ring of muscle in between which twitched every now and then.
"You'll understand very well in a moment," Lockhart assured him, then moved away to take off Luffy's shorts entirely, then worked on his own belt, taking his time to slide them off his hips. Luffy tried to see what was going on behind him, but his binds kept him from turning his head very far. Lockhart noticed him trying to look and sent a sexy growl in his direction. Luffy cringed.
Once his pants were off, Lockhart, rock-hard, lazily waltzed over to where Luffy was beautifully on display. He gave the small, round ass-cheeks another playful squeeze before realising something.
"Oh no, you don't seem excited at all. We'll have to change that." He reached in between Luffy's legs and fondled the immature little dick, watching it slowly rise to attention against its master's will. Luffy made a small noise which sounded something like a sob and he squeezed his legs tightly together.
"Don't touch that, it's embarrassing!" he moaned.
"Don't think like that; it's supposed to feel good," Lockhart encouraged in a soft voice. Luffy moaned again and bit his lip. Lockhart smiled at the submission before dipping his fingers in a bottle of ink, coating them thoroughly before thrusting three of them at once into his tight entrance. Luffy wailed in shock, squeezing his eyes shut and kicking his feet. Lockhart had to back away lest he get kicked, and pulled out his wand, binding Luffy's ankles to either side of the desk to keep them there. "Naughty," he chided.
"Wh-wha..." was all Luffy could manage. Lockhart grinned lecherously.
"It'll feel good soon," he assured. Luffy shuddered. Lockhart stroked a hand down his back in a soothing gesture before plunging the three fingers back into the child's behind, thrusting in and out with speed. Luffy groaned, not sure if the feeling was good or not.
"W-waaaiiit," he protested. Lockhart drew back his hand and smacked Luffy's rump hard enough to leave a red mark on his skin. Luffy gasped and choked on his own spit, effectively shut up.
"Good. Bad boys get punished, you know. That's why you're here." Luffy nodded hastily. "Will you speak again?" Luffy shook his head. "Good."
Lockhart resumed what he was doing for another few seconds before pulling his fingers out and positioning his swollen cock at the boy's virgin entrance, plunging in without a moment's notice. Luffy let out a strangled scream, head tipping back as far as he could manage and eyes bulging out in shock.
"Auuugh, Merlin yes!" Lockhart grunted, shutting his own eyes. "Fuck yeah, you're so tight!" he growled. Luffy whimpered. Lockhart ignored him and slammed roughly in again and again, swearing and grunting on each thrust. It didn't take long for him to force an orgasm out of Luffy before he was brought to his own, ejaculating hard into Luffy's defiled ass with a long moan.
Once he was done, he slowly pulled away, wiping himself off with a tissue and pulling his pants up, buckling them up. With a wave of his wand, Luffy was released from his bonds and he slowly slumped to the floor, white cream dripping from his behind.
"Clean yourself up," Lockhart ordered, tossing a box of tissues at Luffy, who nodded and slowly obeyed, wiping away the physical evidence of their activities.
Lockhart waited until Luffy was all done and had put his pants back on before grabbing him by the vest and yanking him to his feet. He pressed his mouth to Luffy's forcing his tongue down the young boy's throat. Luffy gagged slightly and made a noise of protest but couldn't find the strength to push him away.
"...Tomorrow, 10 o'clock. You have detention again. Be here or else," he commanded. Luffy nodded slowly. "And this time, make sure your tight ass is prepared before you get here." And with that, he sent Luffy away to bed.