After about a month of this, Emma decides to leave the lawn early- she's finished her letter to her parents, and wants to drop it at the Owlery- so Jenny is left to her own devices. Bored, she examines the forest. It's only supposed to be unsafe at night, right? It won't hurt to go wander around a little in search of unicorns. She won't go very far.
And if she's lucky- unicorns.
Half an hour later, Jenny is deeply regretting her idea. She is completely lost, and the forest has gotten much darker and gloomier. She would go back, if she had any idea where to go. She's taken to making little piles of rocks, to attempt to mark her way; unfortunately, so far all this has told her is that she is definitely going in a circle.
The next time she re-encounters a pile, she branches out to the left instead. She's pretty sure she came from that direction, so maybe-
Cold.
Jenny is friends with Miranda. Miranda has been compulsively researching Dementors all year; she knows what it means, this cold, the screaming terror. But it's so much worse than anything ever, ever said it would be. She's frozen to the spot, unable to move, brain screaming in terror.
And then the Dementor appears. Slowly but visibly, it approaches her. Is it bigger than the books said they should be? She thinks it is. It's already looming and it's not even close.
Frantically, crazy with fear, Jenny does the only thing she can think of- she shifts away her mouth.
The Dementor stops, seeming to hover in place. Jenny stays frozen in place. The Dementor doesn't seem to be planning to Kiss her... but it's not moving, either, and she's still stuck.
Oh, God. Now what?
"Okay, kid, breathe, it'll be okay." He puts a hand on her shoulder calmingly. "The paths in the woods aren't great, I'm sure she's just lost. Now, who's missing, exactly?"
"Jenny's in the forest? - are you positive? If she tried to get into, I don't know, our common room, while we weren't around...?"
"I'm not totally sure? But we were out studying by the forest this afternoon, and she was wearing her cloak, and it's not back in the room and she hasn't been seen since and I can't think where else she would have gone with it that she could be gone this long?"
He smiles at them. "Worried about your friend? I suppose I'll allow it. But stay close to me and do as I say, mind, the grounds aren't safe without a teacher at night."
"Point Me", he murmurs to his wand. It spins, and points directly into the forest. He sighs. "In we go, then. She must be lost."
Emma follows, sticking close to Miranda and Karen, and thereby to Professor Fisher. She does not like this forest.
"See? There she is," Scott says in relief. He jogs over to where she's waiting-
-and sees her frantic eyes and eerie, mouthless face too late. He's wrapped in a shroud of cold, cold, cold, and he doubles over, gasping, before slumping forward unconscious.
In the woods behind him, something very, very large stirs.
They're not supposed to be that big.
But Miranda knows what it is, and when she looks at it - numb in the face, like it sprayed her with ice or anaesthetic or like she isn't there at all - when she looks at it the thing she was almost onto, rereading that one chapter for the tenth time to understand, clicks.
There are numerous hypotheses about the metaphysical implications of the Dementor. Many suppose it to be, simply, a monster, with no greater symbolism; others have likened it to the torporous sadness that befalls susceptible minds; it has been likened to everything from inevitability - for they cannot be destroyed, only diverted - to darkness - for obvious reasons. A poet, looking after his exposed son, compared the Dementor to death itself -
But Death is not inevitable. The Philosopher's Stone existed once, it could be made again. There is surely more magic waiting to be discovered.
She doesn't know how to make the Philosopher's Stone on the spot. Let alone how to spontaneously invent a new Dementor-killing spell. The cold is trying to make her give in to this discouraging fact.
But she has a very, very enthusiastic wand.
She brings her shaking hand to her hair, and pulls the chimaera-hair wand out, and she's read the chapter ten times, she knows the motion and the words -
"EXPECTO PATRONUM!"
It's not an animal, even a chimaera. It looks like - a person. A genderless, giant, graceful person of silver light, pouring forward from her wandtip towards the unreasonably large dementor. They're of a size.
And when the glowing person wraps its arms around the monster, they are no longer of a size.
The dementor shrinks, and screams, and shrinks, and Miranda holds her wand up, trembling.
Jenny crumples to the ground. Her face reverts to normal and she starts to sob hysterically.
Emma realizes she was screaming. Funny, she hadn't even noticed. She forces herself to stop, and promptly hides behind Miranda. "Oh my god oh my god oh my god," she whimpers, mostly to herself.
It's such an enormous Dementor, why is it so big -
But finally there doesn't seem to be any of it left.
Its cloak crumples in the Patronus's hands, and falls to the ground.
But, seeing the Dementor crumple, she gives up and runs for Jenny. "Jenny, Jenny Jenny Jenny, are you okay, what happened?"
She wraps her arms around Jenny and starts to cry as well.
There will be no coherency out of Jenny for a while. She is going to right keep sobbing, just now on Emma's shoulder.
Professor Fisher twitches, and then groans. He does not seem in any shape to get up just yet.
"You did it," breathes Karen. And: "We need to all go inside and get a lot of chocolate as fast as we can..."
Emma manages to get Jenny upright and helps her move towards the others. "I can get her," she says breathlessly, "can you guys manage the professor?"
The Patronus scoops up the professor off the ground, and when Miranda takes a step, it follows.
"Yep," she says.