There's a while, basically everything between does it look real to you, where you are and the Doctor making her the little ramp, where Oswin doesn't feel like anything's going to be remotely okay ever again.
Then the Doctor - looking entirely too smug for a man who hasn't done anything cleverer than reinvent the triangle - makes her a little ramp so she can roll in and out of the TARDIS by herself, and she starts to feel like even if things aren't okay now maybe they could be someday.
After the Doctor shatters her sanity-preserving dream she can't pretend any longer, Oswin knows that she is a Dalek. She's aware of her wheels, her eyestalk, and her gun. She's hyperaware of the gun, much as she tries not to be, because there's some tiny, awful, Dalek part of her that wants to use it.
But equally true, Oswin knows that she is a, frankly, adorable young woman in a very fetching little red number and a pair of kick-ass boots; it's just unfortunate that on the outside she looks like a kettle caught in a compromising position with a plunger and an egg-whisk.
Worst case of body-dysmorphia ever, really.
It's awkward, at first.
"I'll have to talk to her, the TARDIS," says the Doctor. Placing his hand on Oswin's shell casing only to jerk it away as though he's just been caught feeling her up at the school disco. "Explain about you, um, as best as I can."
Oswin thinks he's looking for an excuse to leave her behind somewhere. He has to offer to show her the stars, she saved his life, Nina and the angry Scottish girl too, but he won't be disappointed if his ship refuses point blank to have her aboard, she thinks.
As luck would have it Oswin and the TARDIS get along splendidly, and why wouldn't they? Two brilliant, beautiful women like them.
The TARDIS deletes some inconveniently placed staircases and widens the corridors to accommodate Oswin's new... What's a word for girth that isn't girth?
For her part Oswin manages to hack into a subroutine where the TARDIS has had an itch for at least three centuries.
For all the occasions where it turns out to be actually quite useful--
"Don't blink," the Doctor orders. "Oswin, whatever you do, don't blink!'
Oswin swivels her eyestalk to stare at him.
"Yes. Right. Carry on, Oswin."
--there are still moments when the Doctor forgets and looks at her with an expression of such fear and loathing...
Oswin supposes she can't blame him for forgetting. Sometimes Oswin forgets and she's got I am Oswin Oswald, I am not a Dalek, I am human on 24/7 replay in her head.
Still, she hates it when he looks at her like that.
Anyway, if she had a chin like that she'd take care not to pass judgment on other people's outward appearances, thank you very much.
Another important lesson Oswin learns is that creeping up on the Doctor while he sleeps and shouting, "EX-TER-MIN-ATE!" in his ear is only funny to her.
Well, to Oswin and the TARDIS.
The upshot of that is that the Doctor spends the morning fiddling about inside her shell-casing looking for a way to get what he calls her "soufflé girl" voice back.
"I've never let a boy fiddle my casing before," Oswin says.
That, actually, is another new thing. Oswin's attempts at flirting are now usually met with outright terror, and once with sincere scientific curiosity.
Oswin celebrates the return of words of many syllables to her vocabulary by talking a mile a minute for three days straight, until eventually the Doctor brandishes the sonic screwdriver at her and threatens to change her back.
Oswin thinks he's just jealous because he's finally met someone who can out-talk him.
They end up in a Dalek prison camp.
Actual Daleks, not the fuzzy girl-genius variety.
Not this again, Oswin thinks, trying to look Dalek-y and say "exterminate" in time with all the others.
And it takes the Doctor a depressingly long time to find her after they become separated.
"Do you know how many Daleks there are on this planet? And they all look the same. At one point I was trying to stage a daring rescue of their supreme commander," he complains as they hurry back to the TARDIS. "I'm going to make you a sign so that I can find you next time this happens. Or paint something on you: Property of the Doctor, maybe."
He does, too.
Oswin gets her own back when the TARDIS crash-lands in the bottom of a quarry and the Doctor has to push her to the top, groaning and grumbling all the way.
"Don't you have a levitate button in there?" he asks, leaning heavily against Oswin to catch his breath.
She probably does, she could probably even find it if she looked.
"I'm so sorry and I've made you a soufflé," says the Doctor.
Oswin knew already - total screaming genius, remember? - that any attempt to remove her from the Dalek shell would probably kill her and leave the Doctor with an enraged Dalek who knows all about the inner workings of his TARDIS. But hearing it from someone else, that makes it real in a way that it wasn't before.
"I'm going to be a Dalek forever, then?"
"No. Oswin, no." The Doctor reaches out and touches her shell casing, gently this time. "You are Oswin Oswald and you are human. You have to remember that."
Oswin wonders if it should make her feel better or worse to know that the Doctor will be the one who stops her if she ever forgets.
"Your soufflé is collapsing," is all she says.
The TARDIS doors open and they walk - well, the Doctor walks, Oswin rolls - out into the light of a different sun.
"I'm the Doctor and this is Oswin Oswald, she's my best friend," the Doctor announces.
Their audience is one cock-eyed flightless bird, which looks distinctly unimpressed.
Still, it makes Oswin smile to hear him say it.