Twice Upon a Time provides a perfect showcase for Capaldis impatient, expressive, oh-so-ScottishDoctor.
Your face… its all over the place, Twelve remarks.
And, it seems, they can also change actors.

Credit: Simon Ridgway/BBC
I dont suppose either of you is a Doctor?
Post title-sequence, we see the story from the Captains point of view.
and a new guest commenting that its bigger on the inside.
I thought so too, Twelve deadpans.
Glad its not just me.
World War I, Captain says.
What do you mean, One?
Not quite convinced that hes looking at his future self, One introduces Twelve as his nurse.
Older men, like women, can be put to use!
You cant say things like that, Twelve replies.
Ones lets call it a less-than-PC attitude is just one of the fun ways our two incarnations clash.
(This whole place could use a good dusting.
Obviously Polly isnt around anymore.
just, just stop saying things like that.)
Sunglasses vs. a monocle.
Twelves rock star electric guitar.
Her, turns out to be Bill Potts, back from the dead, or so it seems.
Its a gift for Twelve, who exits the Tardis and gives her a massive hug.
But, as weve learned, never trust a hug.
Its just a way to hide your face.
Happy as he is to see her, Twelve isnt convinced that Bill is still alive.
My friend Bill Potts was turned into a Cyberman.
She gave her life so that people she barely knew could live.
Nobody imitates Bill Potts.
Nobody mocks Bill Potts.
The glass woman identifies herself as Testimony, a being (beings?)
The Testimony takes up his Tardis, but with two Doctors, we get two rides.
And so, of course, thats what Bill is.
But, the Testimony is surprisingly, not sinister at all.
Not an evil plan, Twelve says.
I dont really know what to do when it isnt an evil plan.
What is anyone supposed to be except a bunch of memories?
Im Bill Potts, and Im back.
Thats the trouble with hope, he says, about having to go back.
Makes one awfully frightened.
Questions are kind of my thing.
How are you with answers?
By any analysis, evil should always win, One replies.
Good is not a practical survival strategy.
It requires loyalty and self-sacrifice and love.
And so, why does good prevail?
What keeps the balance between good and evil?
Maybe the Doctor is the one real fairytale.
He asks the Doctors to look in on his family from time to time.
And then he gives the name.
One promises to look in on them from time to time.
you’re free to trust him on that, Twelve confirms.
But just then, theres singing.
Silent Night in German drifts from across No Mans Land.
And we get the second beautiful revelation of the episode: Its Christmas, in 1914.
(That real armistice is so heartwarming, it will make you tear up at aSainsbury commercial.
Never happened again, any war, anywhere, Twelve says.
I think Im ready now, One says.
And the Doctors say goodbye.
The Captain gives Twelve a confused salute, indicating that he probably doesnt remember anything that just happened.
But the Doctor of War found a way to bring him home to his family.
But Twelve isnt ready yet.
Sitting in the cold, he invites Bill Potts to go for one last walk.
Letting go of the Doctor is so, so hard, isnt it?
And dont go forgetting me again, she says, Because quite frankly, that was offensive.
Cant I have peace?
His former companions, the Testimony, disappear.
Time to leave the battlefield, he says.
And then we get Capaldis final monologue, his painful, wobble through the Tardis before death.
Well, I suppose….one more lifetime wont kill anyone.
Well, except me.
No one would understand it anyway.
Children can hear it.
Sometimes if their hearts are in the right place, and the stars are too.
Children can hear your name…Laugh hard.
We see her eyes first, hazel eyes.
And then we see the Tardisthroughher eyes.
And thats where we leave her, falling through space, with endless possibilities, and an open future.
That bloke that Bill was talking about?
That bloke that travels around who keeps the good from being defeated by the evil?
Well, he doesnt always have to be a bloke.