The Doctor frowned at his favorite chess set in irritation. The pieces were heavy and ornate, carved from hematite and lapis lazuli, and he was absolutely certain that this was not the configuration he'd left them in. Moreover, he was also absolutely certain that this had happened before. "You can take tidying up a bit too far, you know," he muttered to the TARDIS. It had to be the ship, after all. Either that, or he was losing his mind altogether. After all, the only other person aboard was Rose, and fond though he was of her, he could hardly imagine a nineteen year old of her background having a taste for chess. Shrugging off his annoyance, the Doctor settled into a chair and studied the board, quickly becoming lost in a new strategy.

The Doctor played until his time sense made him aware that Rose had slept for nearly eight hours and would be waking soon. He headed off to the galley to make tea, leaving the game unfinished. The next time he had a chance to settle in the library with his chess game, he found that it had progressed by several moves. He played through the endgame, then reset the board and started over, once again leaving the board mid-game.

And then it happened again. And again. It had to be Rose - there was simply no other explanation, but he never managed to catch her in the act as their strange, intermittent game continued. Until, one night, he did.

The Doctor had been tinkering for hours, and the TARDIS finally let him know she'd had enough, showering him with sparks and deadlocking her access panels. He sighed, knowing when he was beaten, and headed off to the library. Rose was surely long since asleep, so he thought he'd wile away the hours until she woke by experimenting with a new chess strategy he'd heard about on Altair 9, way ahead in the 61st century.

He paused silently in the doorway, as he caught sight of her, hunched over his chessboard, chewing her lower lip in concentration. She hesitated a lot between moves, referring often to a book, but she kept playing, smiling triumphantly when she managed to capture the queen. He slipped back out of sight when she moved to gather her things and get up.

A few nights later, he joined her in the galley for tea, carrying a polished wooden box under his arm.

"What's that, then?" Rose asked.

"Present for you," the Doctor said simply, sliding the box across the table to her.

She gave him a wonderful smile, her eyes shining as she lifted the lid, revealing a beautifully elegant chess set. The pieces were delicately wrought of crystal and rose quartz.

"I picked that up ages ago, from a market on the Rings of Akhaten. I'll take you there someday - you'll love it." He didn't mention that the chess set had been a gift for Susan. A bit much to explain, that.

"Doctor…I…it's gorgeous. Thank you."

"Fancy a game, Rose Tyler?"

She bit her lip in consternation. "I'm not good enough yet. I was tryin' to teach myself, so I could play with you someday, but…"

"Haven't we been playing, all those times you snuck into the library? Dead clever, you are. You'll manage. We'll take it slow. Trust me, this is one of those things that's definitely better -"

"With two?" Rose finished, grinning cheekily.

"As a matter of fact, yes. Now help me set up the board. You get the pink pieces," the Doctor said rather pointedly.