Penny breezes into the apartment with her coffee-mug in hand, intent on milk and maybe a little mischief. Sheldon is sitting in his spot, scowling at something that looks like a piece of modern sculpture. She wonders if it is one of his molecular models, but then she recognises the shape of one of the pieces.

The boys have a surprising number of board games, despite their fondness for tech. She'd had to threaten something violent to Howard when he'd suggested Twister. And there is the never-to-be-repeated 'hilarity' of Trivial Pursuit, Warlords of Ka'a or even Research Lab. And then there was the time she'd played chess with Leonard.

She knows she shouldn't have done it, but really, Leonard had treated her like a child when he was telling her the names of the pieces. And when he hadn't recognised the Latvian Gambit, she'd simply chased him all over the board, whilst playing up her 'dumb blonde' persona. Because she'd spent every Sunday afternoon as a child sitting with her Grampa, and she knows her Ruy Lopez from her Capablanca. Oddly enough, Leonard had never suggested they play again.

Now, more out of a desire to bug Sheldon than anything, she plumps down in the armchair, and starts asking ditzy questions. He twitches, huffs, and then delivers a lecture on tri-dimensional chess. (And all the while, Penny eyes the board, thinking fast, because this requires spatial awareness, a certain amount of cunning, and a ruthless streak.)

And then she basically runs his ass over at warp speed.

Sheldon boggles at a laughing Penny, and then his eyes narrow, jaw set. He starts to reset the board, quick, brisk movements.

"Best of three."

The corners of his mouth turn up, an imperceptible amount. She is always his most worthy opponent.