"You're not meant to exist," the Doctor said, rubbing his palm against his chin as he pondered this latest mystery. He slipped on his specs and squinted at the TARDIS screen. "Readings say you're human."
Hiro blinked his confusion. Of course, he was human. What else would he be?
"Apart from this one blip of DNA," the Doctor continued, tapping at the screen with his finger. "See it?"
Hiro saw nothing but a swirl of circles slipping along each other like cogs in a watch, incomprehensible to him.
"My people, the Time Lords, we thought of ourselves as being completely unique in the Universe because we had a genetic predisposition towards time travel. I mean, we built our entire civilization upon it. Fish gotta swim. Birds gotta fly. It's all there in the DNA, in the blood. Gallifreyans? We gotta travel temporally."
"So," Rose interrupted, staring at the screen. "This all says Hiro's got the same DNA as you? As a Time Lord?"
"Well," said the Doctor. "Hiro, you're still human. Still got the lifespan of one. The mentality of one."
Rose pressed her hand on Hiro's chest. "Still got the one heart," she said, grinning.
Hiro flinched a little. A hero must stay chaste, after all.
"Exactly!" the Doctor said. "So, human. Three billion nucleotide base pairs in every strand of your DNA, Hiro. Two billion nine-hundred ninety-nine million nine-hundred ninety-nine thousand nine-hundred ninety-nine of those pairs completely identifiable as Homo sapiens." He paused, slipping his glasses off. "And one not. And this 'one not' is eighty percent identical to the pairs that make up the time travel gene. The Gallifreyan time travel gene."
"So, humans can evolve that gene?" said Rose, her arms crossing as she nodded towards Hiro. "You've got some competition, Doctor!"
"No...No, it's not as simple as that. Hiro's ability only manifested itself a scant few weeks ago."
"But," said Hiro. "I have trained for months before so I can develop my power. I tried to move the hands of a clock backwards."
The Doctor pressed himself against the TARDIS console, shutting his eyes to concentrate. "Time travel via mind manipulation. My people had myths about it, legends about Time Lords who'd just think of where they wished to go and BLOOP there they were. They were able to tap into the power of the Time Vortex itself."
"Like...what I did? On the GameStation?" Rose asked.
"And they all burned, Rose. All of them. The Time Lords realized that the brain's just meat. It can't handle the whole of time and space running through it all the time. So, build a machine to handle that and hey presto. Surfing through the Vortex in a TARDIS. But Hiro's brain. He...you seem to be able to access the Vortex without taking in any of its power. Your brain seems unaffected by it. Like tuning a radio in between stations. You can get the gist of the music, but you can't hear it clearly because of the static."
"When was the last time you saw anyone use a radio, Doctor?" Rose asked with a smirk.
"Well, difficult to get static on an iPod anyway," the Doctor said dismissively. "Hiro, this ability you have, it will change the entirety of the human race."
"But," said Hiro. "The others? They have different powers. Better powers."
"Healing. Flight. Super-strength. All abilities that only affect the individual involved. But time travel? You're tugging at the very strings that hold reality together. Before you came about, only one race in the entire history of the universe was able to do that, and only one race was able to tightly control it."
"And now?" Hiro asked, his hand gripped tightly on the hilt of his sword to help steady himself.
"That hasn't changed," the Doctor said. "My people were sworn to protect the fabric of time and space from anything that might rend it apart. Hiro Nakamura, you're my responsibility now."