By their very nature, Gallifreyans did not encourage physical contact. Sexual reproduction was socially unacceptable, so there was no point in the act itself nor in any other sort of romantic actions to bring about the act. They didn't hug or lean into one another when they sat. There were no reassuring pats for an upset friend or a child.

The only exceptions, though rarely seen, were between those who shared a Soul-Bond. They were easy to pick out of a crowd because they walked hand in hand. That contact, with their minds open to one another, was considered to be the most intimate of joinings.

This being the case, it took a long time for the Doctor to get used to Earth customs. He tried to blend in as much as possible, and humans seemed to thrive on contact. Everywhere he went, no matter what year it was, people were touching each other. He even learned that human newborns required physical contact to survive. Eventually, he adapted. He discovered that he didn't mind hugs all that much, and that kisses could be quite enjoyable (though he was usually startled when one of those happened). He even held hands with his companions sometimes.

Oh, make no mistake…it wasn't a Soul-Bond sort of thing. No, it was usually more of a Run-For-Your-Life scenario. His mind stayed firmly closed, and even if it didn't it wasn't like the people on this planet shared the same sort of psychic abilities his people possessed.

Then, because of one little Earth girl, everything changed.

oooOOOooo

He wasn't even sure she realized what she'd done.

He was tired that day, so tired. They had narrowly escaped mortal peril yet again. Out for a walk on a beautiful planet with purple grass, he hadn't noticed when they'd crossed into the hunting grounds of a wild Lupania. Resembling a cross between an Earth grizzly and an arctic wolf, the creature was exceptionally territorial, and they'd quickly found themselves literally running for their lives. He hadn't been overly worried about himself…he still had a few regenerations left. But Rose had been in danger, and he wouldn't have been able to protect her if the animal caught them; sonic screwdrivers didn't have much effect on the giant creatures. If that hunter hadn't appeared when he did, the Doctor would have lost her.

So they stood inside the door of the TARDIS, still holding hands, neither one willing to let go just yet. They were both a mess, clothing torn and scratched from the headlong plunge through the forest as they tried to escape. Apparently his hair was more out of sorts than usual as well, because Rose reached up to straighten it.

As she worked, her fingers grazed his temple…and Time stopped.

oooOOOooo

She blinked. "You're in my head," she stated. She didn't sound angry, just puzzled. "That's never happened before."

There was a question in her eyes as she looked him, and he found himself at a loss. How could this have happened between a Time Lord and a human? He had no idea how he was supposed to explain something he didn't fully understand himself.

Rose wasn't quite sure what was going on, but whatever it was had linked them somehow. As she tentatively brushed the edges of his mind, she could tell he had a theory about what had happened.

"What's a…Soul-Bond?" she asked.

He was afraid, and he started to pull away, closing his mind. She stopped him by squeezing his hand, not letting him go.

"Don't do that," she begged. "I can feel you trying to shut me out. I…I don't know what just happened, but I don't want you to leave." She colored slightly. "I sort of like having you there; you're…warm. I know that doesn't make any sense, but…"

The Doctor took a deep breath. "A Soul-Bond," he said, interrupting as he took her other hand, "is something that used to happen on my planet when two people were, in your human terms, 'perfect' for one another, on every level. Their minds joined, and they were always with one another, even if they were separated by physical distance. It was special…it didn't happen for everyone." He exhaled shakily, feeling her presence wash through his body and mind, bathing him in light. "And it's never happened to me before."

As she thought that over her eyes unfocused slightly, like she was looking at something intangible. "There's something…the Bond's not complete yet, is it?" she ventured.

The Doctor shook his head. "When you touched my temple, you initiated the Bond…sort of like sending out an invitation. I still have to accept."

"Oh," she said softly, her eyes darting away. "Well, I mean…you don't…I…I shouldn't…"

"Rose," he interrupted. When she wouldn't look at him, he reached out and tilted her chin up until she met his eyes. Without releasing her gaze, he moved his hand until he gently brushed her temple with his cool fingers.

oooOOOooo

When he lost Rose Tyler, he lost so much more than just a companion. He lost half of his soul.

And though he would have other companions, and would most likely hold their hands, never again would he open his mind and his heart.