This short story picks up at the end of Yu-Gi-Oh DSoD Movie.
See summary here: yugioh. wikia com /wiki/Yu-Gi-Oh!_The_Dark_Side_of_Dimensions [Spoiler warning]

Mokuba firmly grasped his big brother's hand. It was cold, colder than usual, pale, paler than usual. Seto's body was neatly fit into the pod, machine closing in on his legs, wires connected to his head. At first glance, you could have thought he was just asleep. Like he was sunken into one of his virtual reality games yet again. But this time was different.
"Nii-sama… Please come back soon…"

With slow steps Kaiba dragged himself through the endless vastness of the desert. His coat hung loosely from his shoulders, still kept in place by his new Duel Disk. A few wires and antennas kept glowing and beeping softly.
He had already made it. He was already there. Saw the castle, touched it's surface with his own bare hands. Stepped inside the palace, steps echoing through the huge hall.
He sat there on his throne as if he'd waited for him. Surely he must have known. He always knew what went on in this damn stubborn head of his.
A cocky smile graced Atemu's face when he stood to accept Seto's challenge.
It would have been perfect. Would have been perfect, if he didn't collapse. The lights faded to black. His body slowly dissolved into dots and pieces until he faded into nothingness.

A crushing pain in his head pulled Seto's consciousness back. He was surrounded by dunes again. Turning around and around, wherever he looked, just miles of sand. The sun burning down harshly, worsening his struggle. But he had to get up. Get going. He needed to look. Needed to continue to search.

It was not the first time that this had happened. Struggling through the endless hell of heat and sand until he fell to his knees. Digging his fingers into sand, grabbing a small stone to make another mark. An angry red line on his arm, the seventh one.
It was not the first time he found himself back in the desert, stumbling and crawling through sand. It was not the first time he touched the castle walls. Not the first time it transformed into a palace right before his eyes. Not the first time the image of a pharaoh fluttered before his eyes.

Seto wasn't able to keep his eyes open this time when the figure gracefully rose from his throne.
He didn't notice the arms softly embracing him, keeping him from crashing to the floor. He didn't notice the room changing into something different, a modern laboratory, blue lights illuminating the otherwise dark and sterile room.

"It is time to return, Seto…" the voice whispered, sadness betraying the strength it usually radiated with. Two golden bracelets graced his upper arms, giving away his true identity.
An artificial intelligence, a program in just another virtual world. Created by the memories of none other than Seto Kaiba himself, he still wasn't any more than that.
An Illusion, a fata morgana in a sand castle, shaped by the dreams and wishes of his creator.

Blinking, Seto's eyes struggled into focus. He was back, lying in his pod. His virtual reality pod. He had never left, had never made it out of his own little illusion.
A single tear stole it's way down a pale cheek.

[lost in an illusion]

This is one of my first attempts on writing FanFiction. I hope you liked it and I'd appreciate your reviews :)
If you want to see and read more of my crap, I'm very active on: hiramiyugioh . tumblr . com.
Thanks for reading *-*