The dementor had to bring the damaged soul to her. She had asked for it, and the dementor didn't have a choice.
I... don't know? Dementor POV, not something I ever tohught I'd do, but you know, things happen. Teninch, I guess. Barty Crouch Jr and Bad Wolf or Rose Tyler and the Doctor or whatever you figure it to be.
Let's be again
The dementor slowly slided along the path, headed for the tall, old house standing ominously in the shadows of a cliff, cradling carefully inside itself the soul it had just collected. This was it. The moment to get rid of her threat. The moment they would all be free again. Free from her everlasting stare, from her surveillance.
She wouldn't have to nor want to keep watching over all the dementors in the world, not as soon as she'd have gotten what she had asked them for centuries ago.
The dementor reached the house, and its head, covered in a dark hood, looked up to the faint golden light emitted by the polished windows. It had no idea what she was, why she wanted the soul, but... – she looked like a woman, certainly, but she wasn't human, of that the dementor was certain. Not only had she been waiting in that house for half a millenium now, but it also couldn't pick up anything from her, no feelings, no despair nor a hint of happiness. Only a burning sensation, something no dementor had ever felt except near her.
Had it been human, it would have compared the woman to a burning sun in a desert of sand.
It was only a dementor, so it didn't.
The door pushed itself open, just as the dementor put a cold foot on the house's treshold.
It passed by a blue box, about twice as large as a phonebooth, without giving it any attention. It had always been here, decayed and not very interesting, for as long as the dementor could remember. Not that it bothered. It wasn't like there was much that really interested a dementor except sucking happiness out of people, and possibly a soul or two if it was lucky.
This one particular dementor wasn't exactly lucky, as it was. Sure, it had just "eaten" a soul today, and not every dementor could claim to such a thing, not with the harsh control wizards had on them and that they tolerated for fear of being hunted to the end of the world, in a place where no humans resided, where there was nothing to eat. But it wasn't going to be able to keep the soul to itself, to digest it properly.
It was the deal they had with her.
This soul, this specific soul, was hers.
And the dementors weren't socially inapt enough to deny her what she wanted – more like, they had a bare concept of survival instinct, and that was it. This... woman, or whatever she truly was, could turn them into dust without so much as looking at them.
Which was why the dementor, bearing the newly taken soul of Bartemius Crouch Jr, hovered into the living room of the old, creaky house – whether or not it was actually lived in at the moment was up to debate, but dementors do not debate.
She looked up from the book she was reading, tucking slowly her blond hair over an ear, and her eyes – a golden, misty look to those eyes – fell first on her visitor... before sliding right past it, inside it, beneath the layers of dark and dusty clothes, underneath the rotten flesh of a dementor.
"You have him."
Her voice was flat, without one hint of a feeling in it, and the dementor could feel exactly that, coming from her – that is, nothing. He couldn't feel a thing.
Still, it hissed, in between a ragged breath and a telepathic scream.
I have the soul you requested, Bad Wolf. Will you leave us alone, if I give it to you?
There was something, something that sounded quite like laughter, but that wasn't at the same time, because it didn't have any real amusement in it. Nothing the dementor could feel, past the faint amusement that wasn't really there, a human feeling hardly grasped by the being in front of the dementor. A memory of it, perhaps.
"You speak as if you had a choice, Wraith."
It didn't, and it knew it.
The dementor handed the soul over, careful not to scratch any of it, not to keep even a shadow of its feelings inside itself. It didn't know what the woman would do if that happened, and it didn't want to find out. All it wanted was to leave the old house.
Bad Wolf watched the wretched being leave, then focused back on the wounded, yet warm soul in her hands. Smiling softly, Rose breathed a mist of time over what was left of Bartemius Crouch Jr.
"I've waited for this moment for so long, Doctor..."