This might be a little hard to write someone falling in love with themselves, so it might sound bad. 

Also, this is off-topic, but it's Monday, so I just wanna remind you guys not to stress yourself out (as I always do).

Hope you enjoy reading!

(P.S. I'm doing this in Pokemon XYZ because that's the only series I watched)

He could feel himself almost tearing the covers apart in his sleep. He tossed and turned, groaning with his eyes tightly shut, silently begging for the nightmare to end. He held on to the mattress like his life depended on it. Tears and sweat ran down his face as he gritted his teeth, trapped in unconsciousness. 

For the past days, since the incident with Team Flare, Ash had been having the same reoccurring nightmare. The event of Lysandre trying to control him brought back his other self, even after he managed to hide it for so long. His dark side. 

To the world's knowledge, he was the only one who ever had something like it. But no one knew it was him. Only when he was born, his mother would notice that he'd occasionally turn from her sweet, innocent little boy to a bloodthirsty monster. It only ever showed in his eyes, voice and the things he did. He would never physically morph into a sub-human creature.

Any doctor of any kind would either refuse to examine him or just say he had some sort of disorder. But he knew it was more than that. Something inside him was a part of him. It didn't want to let go. It wanted him, but he didn't understand why.

His eyes shot open as he abruptly forced himself up. His hands were trembling, tears were streaming from his eyes. There was a strange beating in his chest, around his heart, as if something was trying to break free. It was punching his chest from the inside. He lost control of his body as a flurry of dark aura burst through from his neck to his ribs. He paled and began to slowly, lifelessly fall backwards, until a pair of shadowy but caring hands took him in. The shadow began to shape itself into a figure, an exact mirror image of him.

"Oh, no", the figure muttered, it's demonic voice echoing in a distorted way, "You've taken over for too long. Poor little Ash, you must be exhausted"

It appeared to be sinister and loving at the same time. The way it cradled Ash's lifeless body in its arms presented how tender it was towards him.

"Don't you worry", it whispered as it planted a light kiss on his forehead, "I'll take over for a little bit. It'll be fun"

It began to fade and all the darkness pierced its way into Ash's body, causing him to arch inhumanely for a few seconds, his eyes being flooded. By the time he sat up properly, the usual, human-like sclera of his eye was black, and his iris was lightly monotonous, white and grey. Blood of black and red bled from his eyes and mouth as he cracked a terrifying smile.

"We're gonna have so much fun...", he murmured with a disturbingly pitched tone before seeming to evaporate into ash-like dust.

I know that was way to short and hardly any shipping, but I don't know much about this ship and haven't read much on it. But it's still always fun to write these little Oneshots and I wouldn't mind doing another one.

Hope you enjoyed!

Requests are always open, but I'm a highschool student so my schedule makes it hard sometimes. Still, I appreciate it even if you read my writing in the first place, it's really nice :)

Have a good day!