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-
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?
"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.
Emma half hugs, half carries a sobbing Jenny inside, and heads directly for the hospital wing. As she enters, she yells, "Madam Pomfrey? Madam Pomfrey? Help, please help!"
Miranda directs the Patronus, still carrying the unconscious professor, into the hospital wing; Karen is hovering nearby, ready to break the man's fall if the silvery person winks out.
"Jenny," Emma mumbles, "her name is Jenny." She helps Jenny over to a cot and sits down next to her.
Jenny curls up next to Emma's knee and shivers.
"We all need chocolate, especially Jenny," she says, voice shaking a little.
Pomfrey immediately sets to obtaining chocolate. She returns with a large pile of chocolate bars; Chocolate Frogs must be too high of a escape risk. "Here," she says, handing each of the functional girls a large bar of their own and sorting the remainder out into piles next to the two cots. "What happened? Was it a Dementor?" She feels Jenny's hand. "She's clammy, poor dear, it certainly seems like a Dementor... and that Patronus... but wherever did you find one?"
"J-Jenny got lost in the woods and got stuck there with a Dementor and she morphed her mouth away so it couldn't kiss her and Emma got worried and found Professor Fisher and we were with him and came along and when we found her the Dementor was GIANT it has to have been three stories tall and Professor Fisher fell unconscious and then MIRANDA KILLED THE DEMENTOR!" exclaims Karen. "It's gone! It shriveled up!"
Madam Pomfrey just- blinks at her a few times. Then she says slowly, "Why don't I just fetch the Headmistress, then?" She summons a house elf to find McGonagall, and then returns to fussing over Professor Fisher. She occasionally fusses over Jenny as well, but Jenny continues to be half-draped over Emma and she doesn't seem inclined to reshuffle them just yet; not as long as Jenny is eating her chocolate, anyway.
Professor Fisher is slowly coming to. He isn't very coherent yet, but nothing he is saying is particularly child friendly.
And pulls her notebook out of her bag, because she had it, she was taking notes when Professor Fisher was talking to her and Karen -
McGonagall arrives shortly thereafter. "Miss Swan, I hear you have a story to tell," she says dryly. "A summary, if you please?" She eyes Professor Fisher, who has managed to stop swearing but is still quite pale and shaky. "Professor Fisher, I will be wanting your report as well- once Poppy is done with you."
"Yes Professor," says Miranda, closing her notebook. "Jenny went missing and Emma found Professor Fisher while me and Karen were talking to him. And we all went looking for her in the forest and she'd been cornered by this dementor at least three times as big as they're supposed to be and she'd shifted her mouth away so it wouldn't kiss her. And Professor Fisher collapsed, I don't think he was expecting a Dementor. And I knew the incantation for a Patronus, so I made one, and it was a very big Patronus and it killed the dementor and picked up Professor Fisher for me and we all came back to the castle and went straight here."
"I did," says Miranda. "It shriveled up until its cloak fell to the ground in a heap and then it didn't feel Dementory around the place at all."
McGonagall sighs. "We do not need another media circus around this school," she says, mostly to herself. "I must go; we shall need to investigate the Dementor's presence. They were supposed to all have left, after the Battle." She looks at them over her glasses. "Are you all willing to keep this quiet until I have determined what, precisely, happened? I should like to have some answers before the public speculation begins."
"I want to kill the rest of them," says Miranda. "All of them. How long do you want us to wait?"
"Telling others? Preferably, not until we can figure out where the Dementor came from, and why you say it was so large. I would add 'until we know what you did to it,' but honestly, Miss Swan, I expect that to take quite a while." She sighs. "As for killing the rest of them- do please recall, Miss Swan, that you are eleven. And under my supervision. While I fully support any endeavor to rid the world of Dementors, if you wish to participate you will need to wait until graduation."
"I cast a Patronus. I did it exactly like in the book," says Miranda. "I'll show you if you want. If everybody's Patronuses could kill Dementors we'd already know about it."
"Miss Swan, whether or not you did cast a Patronus is irrelevant. You are a child, and you are in school. Wizards have coexisted with Dementors for centuries; they can continue to do so until you are an adult. You are a Hogwarts student, not an Auror, and your Patronus will keep until you finish your studies."
"I cast a giant, person shaped Patronus that killed a Dementor. A huge Dementor. It could keep me safe!"
Flushing, McGonagall collects herself and straightens. "Enough. Back to your Houses, all of you; it's well past time. You can visit your friend tomorrow."