Her chameleon arch is still broken.
Or: her chameleon arch has not been broken for a very long time.
As long as she's a police public call box from a junkyard in Shoreditch in 1963, he'll always have a little bit of Earth with him. He'll always have a little bit of Susan.
For a long time, that suffices.
And then one day he looks at her, staunch and solid in her coat of blue paint that was meant to help a young Time Lady start her life in the universe, and he hurts. And he becomes a soldier.
A soldier, she knows, needs a wolfsister.
She doesn't know where she learned that. The people who made her forgot how to be soldiers many turns of time before her seed was planted.
But she remembers: she remembers when they took things away from her, and took things away from him, and then visits from the bright young soldier with his mustache and his epaulettes and his wolfbrother leaning into his leg, and after the soldier and his wolf left he would slump tiredly against her console and stroke her tenderly and say, "Don't worry, dear, this too shall pass."
She was a police box from Earth for a very, very long time. And a soldier needs a wolfsister.
It's not a difficult change. She can become anything that's larger enough on the inside to contain a universe: living things are easier than nonliving. And she's programmed to take the shape of whatever best matches her surroundings. Her surroundings are: the one who stole her heart, his pain. Her surroundings are: her soldier, who wishes/hopes/pretends he is protecting the Earth.
She waits until he's left her in a safe place while he is on a lonely mission, and she twists her heart to match her soldier's.
Later, she remembers-forward, he will lock away his soldier's self and hide the key, and she'll be his blue box again. Later he will meet a human woman/girl/woman who wears a lot of red and who is big enough on the inside to contain many universes and will know how to cut open a wolf's belly and take out the cold heavy stones that have replaced loved ones and then sew it back up again almost good as new.
Later she'll show the woman how to be her own wolf.
Later he'll leave the woman behind and walk lonely in the sky and, perhaps, he'll need a wolf again.
Now, her soldier walks into a junkyard on a forgotten planetoid in a star cluster that will not have existed tomorrow: and he sees her, dark-eyed, shining silver-blue in the unfiltered starlight, and he wraps himself around her fur, and he cries, and he cries.
A police box is for: Finding someone who can help.
A wolf is for: Being hungry. Being family. Howling to the endless dark even when there is no answer.
She howls. There is no answer.