This is a Yugioh and Doctor Who crossover fic, and I own no rights to either of them.

Set sometime after the anime in the Yugioh timescale.

The Doctor featured is the tenth one (David Tennant), set sometime after Rose but before Martha in the Doctor Who timescale.

Chapter One

It was a day just like any other in the city of Domino. The streets were filled with people as they raced to their destinations during the morning rush hour, roads were clogged with traffic and sidewalks crowded with pedestrians. Outside the Kaiba Corp building people were so caught up with other things that nobody heard the distinguishing sound of the TARDIS as it appeared out of thin air right beside the bushes next to the building.

The pulsing, whining and whirling noises of the TARDIS stopped and the doors to the nineteen fifty's London police call box opened. The Doctor stepped out from his time machine with his brown trench coat trailing behind, as he looked around the setting what lay before him. "Let's see what we have here." He smiled to himself as he approached the three stone Blue Eyes White Dragons that stood guard outside of the entrance in to the KC building.

Inside the building the Doctor walked straight past the reception desk as he headed for the elevator to take him up to the main control room right on the top floor. "Sir, may I see your ID please?" The receptionist shouted after him as she struggled to do her own job and that of the security guard who had been fired the previous day.

"Sure." The Doctor smiled as he doubled back and opened his ID wallet to show the receptionist.

"Your first day on the job, eh?" The receptionist asked seeing that the wallet in front of her identified the man as one of her boss' new researchers.

"Is it that obvious?" The Doctor laughed nervously as he placed his ID back into his coat pocket and made a mental note to try and blend in a bit better.

"I would have remembered someone as good looking as you." The receptionist flashed a flirty smile the Doctor's way and added to warn him. "Mister Kaiba doesn't tolerate lateness."

The Doctor smiled and nodded in return before heading for the elevator once again. He rode it all the way up to the top of the building and exited to follow a corridor round to the huge control room where researchers were busy typing away at their work stations. It had been a while since he had seen technology this advance during the time period he was currently visiting.

"Hey you, let's see some ID!" Mokuba ordered when he spotted the newcomer enter into the room. The Doctor complied and handed his ID wallet to the shorter scruffy-hair boy who quickly handed it back to him, satisfied that the unfamiliar man had permission to be there. "Okay, but next time don't be late, my brother isn't as forgiving as I am."

There was an empty work station across at the far end of the room which was perfect for the Doctor to use as it was almost hidden out of sight from the rest of the room. He made his way over and began to randomly press the keyboard, making it look like he was busy working.

After hearing his brother address the latecomer Kaiba had been stood watching the whole time. Still focusing his gaze on the brown coated man he made his way across to Mokuba. "That guy you just let in, who is he?" he asked.

"One of your researchers." Mokuba replied as he glanced up to his older brother in some slight confusion.

"I choose all of my researchers myself, and he isn't one of them." Kaiba told his brother as he watched the impostor through narrowed eyes. He glanced down at Mokuba who should have known better than to let a complete stranger in his research lab. "Keep an eye on him; we'll soon see what he's up to." He flashed one last glare across the room before he left for his office.

Mokuba could sense that his brother was annoyed with him and didn't want to displease him again. Slowly he moved from work station to work station, keeping a close eye on the impostor who had snuck his way into the building. He wasn't going to let his brother down and would do what it took to keep track of him.

When no one was looking, the Doctor took out a small silver device and pointed it directly at the work station in front of him. Almost instantly every file stored on the Kaiba Corp system, regardless of security measures, was displayed before him in a blur as each flashed on screen for a brief moment. The doctor frowned as the last file disappeared from the screen now leaving it blank. He had been able to read through each file for the short time that they had been displayed and couldn't see any reason as to why the TARDIS had dragged him to that location. Sure the technology that the company was using was advanced for it's time, but there was nothing 'alien' detected within the system. He placed his small device back into his pocket and left to consult with the TARDIS' controls on the situation.

The Doctor made his way back along the corridor to the elevator and was about to ride it down when he heard the voice of the scruffy haired boy call out for him to 'hold' the elevator for him. Not wanting to stand out and draw more attention to himself he did what he thought any other human would do and stopped the doors from closing so that the boy running towards him could enter.

"Thanks." Mokuba panted as he stood beside the Doctor and tried to get his breath back after having sprinted so as not to fail his brother's orders of keeping an eye on the stranger. He watched as the doors began to close but were stopped again, this time by a hand that he knew belonged to his brother, and Kaiba too joined them.

"Have you seen my brother yet?" Mokuba nervously asked the Doctor as Kaiba proceeded silently to the back of the elevator. The doors closed and the elevator began to descend the shaft.

"No, not yet." The Doctor replied politely to the boy's question, clearly unaware that the CEO in question was stood directly behind him.

"He's been dying to meet you." Kaiba heard his brother say as he glared at the back of the man's head and wondered who would be dumb enough to try and sabotage his company without doing research into the identity of who owned it?

The Doctor just smiled in response but didn't say anything more on the subject causing the elevator to fall silent before Mokuba broke it: "I saw you downloading information from the company's database."

Kaiba's eyes widened from hearing Mokuba's comment. He had the best security systems that had ever been created, there couldn't have been anyway that someone could just access the data unless they had gone to great lengths to figure out a way to bypass them. Letting his anger take control he forced the impostor tightly up against the wall and stared down at his little brother with annoyance in his voice. "Why didn't you mention that fact sooner?!"

"Seto, calm down!" Mokuba cried, not paying attention to the tone his brother had used towards him, as he feared for the stranger's safety from the force his brother had used to restrain him. "We're in an elevator, he's not going anywhere." He pulled at his brother's arms but still they remained strong.

"Let me guess, your brother right?" The Doctor wheezed in a rather cheery voice as he looked down at Mokuba, a smile still present on his face despite being pinned tightly against the wall by the CEO.

Mokuba nodded as he still tugged at Kaiba's arms and managed to relax his brother's grip so that the man could now breathe again.

"I want answers and I want them now!" Kaiba demanded. "Who sent you? Was it Pegasus? Siegfried? Dartz?" he reeled off the names of those who had tried to take over his company in the past.

"I have no idea who any of those people are." The Doctor answered truthfully shaking his head and still smiling.

Kaiba was losing patience with the smug stranger. "Who are you?" he growled.

"If you'd like to take a look at my ID." The Doctor carefully attempted to reach for his coat pocket, the move was allowed by Kaiba although he watched the man for any sudden movements he may attempt to make. Taking his wallet out, the doctor handed it over to the CEO.

"It's just a blank piece of paper." Kaiba growled in annoyance at what he had been shown to him and snatched the wallet from the Doctor's hand.

"No it's not." Mokuba looked puzzled as he took the Doctor's ID from his brother's hands and looked at it to see the same details he had seen earlier. How could he have not seen that it clearly stated that the man's name was John Smith? Mokuba stared hard to try and understand what it might have been that made is brother believe that the ID was fake when slowly the details disappeared and left just a blank space where they had once been. "How'd it do that?!" he asked in surprise.

"I'm impressed." The Doctor beamed a smile at Kaiba and ignoring Mokuba's question. He lifted his arms to try and prise Kaiba's from his own. "Very few people can see psychic paper for what it is unless they've been told."

"You're avoiding my question." Kaiba snapped as he shook off the man's arms from his own.

"I'm the Doctor." Came a cheery reply only to be met with silence from the two brothers. "A Time-lord." He added.

"Doctor who and a what?" Mokuba asked, his face wrinkled up in confusion as he handed back the ID wallet to its owner.

"Just 'The Doctor'" he smiled glancing down at the younger brother who seemed more interested than the older of the two. "I travel through time stopping at intervals to take in the sights."

Kaiba rolled his eyes not amused at what was being said. "Cut the crap." He slammed the Doctor hard against the wall hoping that the violence may loosen the man's tongue.

The lights flickered from the sudden force of impact and the elevator slowly came to a halt as it gradually lost power. "That's one nasty temper you have there." The Doctor laughed.

Mokuba typed in several code combinations on the elevator's control panel but nothing happened. "Aw, great! Now we're stuck here." He looked up at his brother. "Nice going, Seto."

Kaiba glared back at his brother after the sarcastic remark and the Doctor took the opportunity to slip free from his grasp at the slight distraction. "I can get us moving again." He announced as he made his way over to the control panel. "And for your information, I wasn't downloading anything."

"And you expect me to believe that?" Kaiba growled, baffled by how the man had escaped from his grasp so easily.

"Believe it or not, it's the truth." The Doctor sighed as he reached into his coat pocket again to produce the thin, metal cylinder, pen like object that Mokuba had seen him using earlier. "I was just looking for something."

"Looking for what?" Kaiba demanded.

"I don't know, I didn't find it." The Doctor shrugged as a small light flashed from the device he held in front of the elevator's controls.

"Just what is that thing?" Mokuba asked curiously.

"My sonic screwdriver." The Doctor replied proudly to the boy who seemed to be taking a real interest in everything he had told him. "It has many uses; it can open virtually any lock, mechanical or electrical device, repair equipment, be used as an offensive weapon – although it can't kill anyone, - and it can even take out screws." He said all of this in one go before the panel fell away from the wall to reveal a network of criss-crossing wires and several hidden buttons.

Again, Kaiba rolled his eyes at the nonsense that was leaving the Doctor's mouth. His brother may have been easily fooled in to thinking that the strange device was some kind of super multi purpose tool that could only exist in science fiction, but he wasn't. It was clear to him that the device was nothing more than a simple electric screwdriver and its owner a crazed lunatic.

"Does this building have a room below basement level?" the Doctor shouted over his shoulder at Kaiba whilst he gently trailed his fingers over the buttons and rested upon one which had been completely disconnected from the circuitry board.

"No. Why?" Kaiba asked suspiciously.

"I think that I've just found what I was looking for." The Doctor smiled as he pointed the sonic screwdriver at the exposed wires and a flash of light erupted out of the end of the device causing the lonely button to become hooked up to the board and full power to be regained. He pressed the button sending the elevator to descend to its new destination.