Nothing ventured, nothing gained

"Whoa... This is... Well..." Thomas said, awestruck.

"What, alien? Mysterious? New?" The Doctor said, switching on a couple of levers and pressing some buttons.

"Awesome!" He clenched his fists and shook them with glee.

"Well, glad you like it, then!" He switched on a couple of more levers and began to pump something behind the 'engine'.

"So, what's this called again? A Lardis?"

The Doctor chuckled, "TARdis. Tee, tah; Tardis."

"Ah, okay."

The Doctor leaned on a rail, "So, where do you want to go, then? We can go backwards, forward, up, down, left, right, diagonally... Anywhere you want, mate!"

"Erm... How about the future?" Thomas shrugged; there wasn't anything he could think of on the spot.

"Righty-O!"

   The Doctor started to pull some knobs and spin something on the 'engine'. More button mashing and knob twisting lead the Tardis to shake. Thomas was caught off guard and nearly fell. The Doctor couldn't help but chuckle as he continued to work his magic on the Tardis.

Seconds later, he stopped and leaned on the rail, smiling, "All done, then!"

"Really? That fast?"

"Of course! Obviously, you know nothing about time travelling to know its effects." He patted him on the shoulder, "Come on."

   The Doctor opened the door and Thomas was blinded by a bright light. It took him some time to get used to it, but the world soon came into view. In front of him was a canal several football fields wide. A bride lead to a white futuristic city with cars that flew above. One of them passed over head, making a warbling noise as the engines revved.

"What... is this?" Thomas was obviously awestruck.

"Now what, when." The Doctor chuckled, "We're in the year 5,000,000,023 on the planet of New Earth."

"Wow... It's amazing what civilization will grow into in billions of years."

"Right. C'mon, let's go grab some grub; I'm starving."

   They went about in the city, Thomas's mouth still gaping from the futuristic sights that were seen. It was hard to take in, some of it. Some questions even began to flow through his head: was there a cure for cancer? Was poverty still a thing? The train of thoughts halted when the smell of food hit his nose. They went up to a foot booth and ordered a simple burger and fries.

Sitting down, Thomas noticed something shiny in The Doctor's jacket, "What's that?" He pointed.

"Ah! That, my boy, is the Sonic Screwdriver; the ultimate key, the ultimate escape device."

"So, it's basically a skeleton key, then?"

"Righty-o!"

"Could I see it?"

The Doctor had a face of concern. He looked at the tool and then at him, "I suppose. Just, do me a favor and don't aim it at your skin; it's a bad idea."

"What, does it hu--"

"JUST, don't do it." The Doctor interrupted.

   Thomas played around with the chrome covered stick, flicking it on and off, trying to figure out how the blue bulb on top could possibly open anything. The Doctor sensed his skepticism and walked him over to a door they were going to have to go through. He gestured to the lock and Thomas flicked the switch on, aiming the blue light on it. A click of the lock opening sounded and Thomas turned it off, amazed that it actually worked. They both went inside and The Doctor couldn't help but see a commotion in the distance; he was going to have to stop it to save anyone from harm. Thomas, however, stayed back.

Curiosity got the best of him and he looked at his wrist, then at the screwdriver, "Oh, what bad could happen?" Flicking on the screwdriver, he aimed it at his wrist and touched it.

   It felt weird, kind of a cold liquid feeling. But, he could see a faint blue mark that it left on his wrist. His eyes opened in horror and started to rub his wrist on his jeans, worrying that The Doctor was going to see that he disobeyed him. As if timing couldn't have gone more wrong, The Doctor sprinted to him, with a look of anger.

"Thomas, give me the screwdriver!" He called out.

"H-here!" He held his non 'tainted' hand out. The Doctor grabbed it and went back into the crowd.

   Well, he dodged a bullet. Looking back at his wrist, he could see the blue mark was gone. He sighed and walked over to the crowd, curious to see what was going on. When he was walking, however, things started to slow down. He thought it was just his eyes, but everything was literally slowing down; even The Doctor succumbed to the sudden time stop. Thomas was worried that either something dangerous was nearby, or... it was the screwdriver.
~±~
   He suddenly felt queasy, weak and just full out not good. He tripped and fell on his knees, panting with exhaustion. Looking at his hands, which were just swirls of color to him, he saw them shrink. He shook his head, rubbed his eyes and blinked some times, trying to focus on the reality. Then, a sudden pain on his back dropped him on his side. He was scared; what was going on?

   His entire body ached and cramped. A tickle on his neck made him quickly get up in fear of bugs, but soon fell down again, feeling the same tickle on his neck on a different side. His stomach squeezed itself and seemed to move whatever body mass around like a tube of toothpaste. His entire body was wrapped in an invisible tarp that squeezed him to death. Eventually, all of the cramping stopped and something more happened.

   Thomas cringed and squirmed, feeling something down below move and shrink. Disappearing from existence, Thomas knew what was going on. Pressure on his chest took that thought away and he screamed in a higher tone of voice that wasn't his. Within seconds, he blacked out.
~±~
He woke up in the Tardis, dazed and disorientated. The Doctor stood above him, having the look of disappointment and utter distrust. His eyes burned a hole through Thomas, "I hope you're happy, then." He said at last, "You've could have been killed.

"What happened?" Thomas' new voice still freaked him out. He was worried that he might have turned alien.

"Well, why don't you take a look." The Doctor pulled a mirror and Thomas saw a girl staring back at him. He was a girl now.

"Oh my goodness!" She said.

"What do you have to say for yourself?"

"Uhm..." She shrugged, "Say hello to... Tracy?"

The Doctor's face didn't move. Then, with a sudden burst of laughter, The Doctor hugged her, "I'm just playin' with ya, lass!"

Tracy was confused, "What?"

"The Sonic Screwdriver doesn't mess with anything; it's just a lock picker! Look: it's completely harmless!" He moved the screwdriver onto his hand several times.

"But... What about the whole 'ultimate escape device'?"

"I lied!" He continued to laugh, "What's better was I knew you were going to touch this, so, I programmed it to fool with ya!"

"So... you turned me into a girl for your own fun?!" Tracy sounded a bit agitated.

"Yea!" The Doctor smiled. She was mad, but she understood the joke; she probably would have done the same if she knew how to use that, "Should I change you back, then?" He flicked on the screwdriver.

"No! I mean... No, not yet. I mean, it's new territory, this." She looked down at herself, "Nothing ventured, nothing gained, right?"

"Righty-o, lassie!" The Doctor's enthusiasm was contagious, "Where do you want to go next?"

"Let's go back home and see how many people can recognize me."

The Doctor laughed, "Aye aye, captain!"