The Game of Making, by
ionlylurkhere.
R. Ten/Martha.
Martha discovers what the Doctor really likes.
Spoilers: S3 Big Bad.
Here is how the game is played:
She tells him an early memory, a formative experience. He explains to her how he could manipulate it to change her personality.
They both become excited.
At the crucial moment, he asks "Are you sure this is what you want?"
And she says "Make me, Time Lord."