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The figure dropped the dark hair into the small vial. As soon as it sank into the thick, bubbling concoction inside, the liquid turned an opaque dark blue, and a sweet fragrance rose from the vial. The figure raised the vial up to the mirror on the wall, as if in good health, then drank it all in one gulp.

Immediately, the figure clapped his hands to his stomach, as though internal organs were trying to crawl out of the body. The figure's skin was rapidly darkening, from its natural pale complexion to chocolate-brown. Within a minute, the transformation was complete. The figure quickly took off his old clothes, which were now way too small, and put on other clothes he had borrowed for this moment. The figure glanced once more into the mirror, smiled with satisfaction at the familiar face, then strode out of the room.

Seamus Finnigan lay on his four-poster bed, his hands intertwined behind his head. It was his last day at Hogwarts before he finished, forever. He had returned to finish his seventh, and final, year, since it had been disrupted the year before, due to the Second Wizarding War. He was excited to finish, but it was bittersweet. The small number of 'eighth year' students had mostly bonded well, with the exception of Slytherins, such as Draco Malfoy, who were subdued after the defeat of the Dark Lord they had supported. Out of his year of Gryffindors, Hermione Granger had returned, as had Dean Thomas. The three of them spent a lot of time together with returned Ravenclaws and Hufflepuffs, reliving memories, and remembering friends who were not with them today. In the morning, Hogwarts had planned a special graduation ceremony for them. Seamus had heard from a reliable source that all their other year mates – the ones that hadn't returned to Hogwarts – had come up, as a surprise. Seamus hadn't told anyone else, though he suspected that Hermione, at least, would have heard from Ron Weasley, her boyfriend. Then, they would all take the Hogwarts Express one last time back to London, before continuing their lives after school.

The door of the dormitory creaked open. Seamus looked up. Only one other person would be entering this dormitory. As in previous years, dormitories were separated by age and gender. Temporary dormitories had been set up for the three eighth years in the attics of Gryffindor Tower. The only other resident of this room, other than him, was his best friend, Dean. Dean closed the door to the dormitory behind him, then walked over to the unoccupied bed. He took off his cloak, and threw it onto the trunk at the foot of the bed.

"Nearly over", Dean grunted, throwing himself onto the bed.

"Yeah", Seamus said, with a sigh.

He closed his eyes, trying to push out the heavy thoughts that were crowding into him. When he opened them, Dean was standing over him. Seamus grinned.

"What, love?" he said, teasing. "Your own bed not comfortable enough?"

Dean smiled as well.

"I'd much prefer to share yours", he replied.

Dean leant down, his hands bracing himself on either side of Seamus' body. Dean and Seamus' lips touched, deepening into a kiss. Seamus reached up to throw his arms around Dean, and drag his friend into the bed with him. Their lips were pressed together; their tongues darted in and out, to taste the other's mouth.

Finally, Dean pulled away. Sitting in the edge of the bed, he pulled off his shoes and socks, throwing them to his half of the room. Seamus propped himself up on an elbow, and sighed as he gazed at his lover. Dean turned back to him, and caught his lips again with his own. His hands explored Seamus' body, first above the clothes, then slipping beneath Seamus' shirt. Rough fingers slid over Seamus' nipples, causing the Irish man to sigh into his lover's mouth. They pulled apart for an instant, as Dean pulled off Seamus' shirt, then mashed their lips together again.

As Dean ran his hands through Seamus' hair, Seamus reached down to fumble at the buttons on the darker man's shirt. He finally undid the last button, and Dean's shirt slipped off his dark body. With heightened passion, now that skin could touch skin, they kissed, moaning into each other's mouths as hands explored. When Dean's hand slipped into Seamus' pants, Seamus threw his head back, and closed his eyes. Dean's hand squeezed Seamus' cock, causing the Irish man to moan.

Suddenly, Dean gasped, and pulled away from Seamus. Seamus opened his eyes, and looked at Dean worriedly. Dean, however, was not looked at Seamus, but at the door of their dormitory. Now, it was open, and a familiar figure stood in the doorway. Seamus stared as well, then his eyes flicked to Dean, who had gone pale, and back to the figure at the door.

"What—", Seamus began to ask, then stopped.

The figure in the doorway was Dean, fully dressed, and with a shocked look on his face. Seamus licked his lips, then tried again.

"What Dark Magic is this?" he asked in a whisper.

The newcomer stepped into the room, and took a few step towards Seamus, and the Dean sitting next to him on the bed. Both of them shrank back from him. Stopping, a few steps from the bed, the new Dean shucked off his cloak, then unbuttoned his shirt, and dropped it to the floor next his cloak.

"It must be Polyjuice Potion", the Dean next to Seamus said.

"But who is it really?" Seamus answered.

There was no reply.

The new Dean took another step forward, and before either one of the men on the bed could to anything, leaned forward, and kissed Seamus deeply. Seamus struggled for a moment, then doubt hit him. He tasted and felt exactly like Dean. What if the original Dean was the imposter? Before Seamus had time to think anything else, the original Dean pulled the newcomer off Seamus, and sat on his chest, holding him down.

"Who are you?" he asked with vitriol. "Why have to taken my form?"

The other Dean fought back, and the two Deans tumbled from the bed onto the floor. Seamus got up, and ran to them before they could harm each other.

"Stop it!" he yelled.

Two sets of identical brown eyes looked up at him, but their owners both stopped fighting, though they didn't let go of each other. Seamus sat back down on the bed, and rubbed his eyes tiredly.

"I don't even know which one of you is really Dean", he said, anxiously.

Immediately, one of them spoke up.

"I'm really Dean", he said.

The other one cuffed him around the head, shutting him up.

"Don't listen to him", he cried. "I was here before the imposter came in!"

Seamus sighed again.

"I'd better get Hermione", he said, rising from the bed. "I'm sure she'll have some potion that can reverse Polyjuice Potion."

"No, don't", both Dean's said at the same time.

They stared at each other, partly bemused, partly suspicious. Seamus sat back on the bed, and stared at them, waiting for one of them to explain. Finally, the one who had spoken initially, looked up at Seamus.

"There's another way", he said. "You would be able to tell by mannerisms that I'm the real Dean."

The other Dean snorted in disagreement, but the first one spoke on before he could butt in.

"All we need to do, is do something that you and Dean have done before, and you'd be able to tell", he continued.

Seamus looked from one dark face to the other.

"I don't like it", he said, rising again. "I'm going to get help."

Before Seamus could take more than a few paces towards the door, one of the dark men on the floor rose, and gave Seamus a tight hug, pinioning his arms by his side as their lips pressed together. Although Seamus knew that this could be a trick, that one of the Dean's in the room must be a fake, the smell and taste of the man kissing him was of Dean.

Meanwhile, the second Dean had gotten to his knees, and had unbuttoned Seamus' pants. As they slid to the floor, Seamus stepped out of then unconsciously. The second Dean stood up, and beginning by kissing Seamus' neck, started to work his way down. When he got to Seamus' nipple, he sucked on it, biting it lightly. Seamus moaned into the other Dean's mouth. Not to be outdone, the Dean that was kissing him released Seamus' arms, now that it didn't seem like Seamus was going to try to leave, and slid a hand into his boxers, giving Seamus' cock a squeeze. Immediately, it began to harden. Goosebumps grew on Seamus as the Dean that was sucking on his nipple worked downwards, his tongue leaving a trail of saliva behind it. After swirling his tongue in Seamus' bellybutton, Dean moved down, kissing the sparse trail of hair that disappeared into Seamus' boxers. A pair of unknown hands pulled down the Irish man's boxers, leaving him naked.

Both Dean's pulled away, and one pushed Seamus onto his bed. Seamus looked up to the mouth-watering sight of two Dean Thomas's staring down at him. While Seamus had been occupied, they had stripped off their remaining clothes. They were still identical, all the way to the slight curve of Dean's cock that Seamus knew so well. The Irish man grinned as two dark men climbed onto the bed with him. The doppelgängers knelt on either side of Seamus, their hands once again exploring his body. One hand curled around Seamus' cock, which was fully hard by now, slowly stroking it up and down. Another hand slid down Seamus' back until it reached his arse. A finger circled the hole, then slowly pushed its way inside. Seamus moaned loudly. More fingers glided over his chest to latch onto Seamus' nipples. One of the Dean's captured Seamus' mouth again, biting the Irish man's lip as he deepened the kiss. Seamus arched his back as a second finger intruded into his arse. His breath was shallow; his mind, which only minutes before was filled with suspicion, was now rewired to only feel pleasure.

Seamus mewled querulously as the fingers were removed from his arse. Before he had a chance to complain, he was pushed onto hands and knees. Something hot pressed against his hole, and Seamus pressed backwards against it, relaxing the muscles around his hole in preparation. The cock slid into Seamus easily. A guttural moan escaped from Seamus, causing both Dean's to smirk at each other over the Irish man's head. The Dean behind Seamus slowly pulled his cock out, then, just when only the head was still embedded in Seamus, he thrust in again, eliciting another moan from the Irish man was Dean's cock hit the sweet spot inside him.

While Seamus was being fucked, the other Dean crawled under Seamus, and lay on his back. One hand gripped the cock that hung above him, which the other began to slowly stroke his own. Pulling Seamus down, he took the Irish cock into his mouth. As one Dean thrust deep into Seamus, Seamus' cock thrust deep into the other Dean. When Seamus looked down to see a cock below him, he began to suck it in return. For a time, the only sounds in the dormitory were mouths slurping on cocks, dull slaps as dark body hit pale arse as it thrust, and assorted grunts and moans.

Finally, the Dean fucking Seamus pulled out. He stood over Seamus and the other Dean, watching them as he jerked his cock. With a final grunt, he came over Seamus' back. Seamus and the other Dean didn't stop sucking each other. After a short time, Seamus thrust into Dean's mouth one last time, and came in his lover's mouth. Dean didn't last much longer. Just as he was about to cum, Seamus pulled his mouth off Dean's cock, and stroked it a few times. Dean came hard, splattering his cum in Seamus' cheek, before the rest dribbled down his cock. Seamus licked the cum off Dean's cock, before rolling off the darker man.

It was then that Seamus and Dean realised they were alone in the dormitory. They stared at each other in surprise.

"I didn't dream there was another one of you?" Seamus asked.

Dean shook his head, as if trying to clear his mind.

"Who was he?" he asked, incredulously. "What was he doing here?"

As they got off the bed, Seamus and Dean noticed a playing card left by the door. Dean picked it up. It was a Joker, but across the image, someone had written in calligraphic letters,

"DOPPELGÄNGER"