IMAGINE: Dean and Sam hunting a dementor.
(h/m)=happy memory
(y/p)=your patronus

"Gabe! What the hell was that for?!" Sam shouted at the shorter, golden haired archangel.

"Welcome to Hogsmead!" Gabriel announced, bowing before disappearing.

"Son of a bitch!" Dean shouted to the surrounding silence.

Meanwhile, you knew exactly where you were, and were looking around in complete awe. You reached in your pocket for your phone to text Charlie, oh to see the look on her face.

"Dammit, there's no signal either Sammy!" You heard Dean exclaim. "What the hell is this?!" You expected Dean was speaking in general so didn't bother turning round.

Replacing your phone, you felt something dig into your side. Pulling it out, a few sparks flew out of the end. A wand! You grinned and turned round, to find Sam and Dean holding wands of their own.

"This is amazing!" You breathed, making a mental note to thank Gabriel when he came to get you.

"Really? He ruined your birthday!" Dean seemed shocked at your reactions.

"Ruined?! This is one of the best possible presents!" You laughed, hugging both boys.

Suddenly, everything went cold. And a dark hooded shape appeared a few hundred metres away. Quickly you dragged Dean and Sam behind a closed shop.

"Was that?..." Dean began.

"Yes. A dementor. What it's doing here I have no clue." You answered, peering around the side of the building. It was getting closer. You looked down to the wand in your hand and back up. 'its worth a shot, right?'

You moved out to stand in the path of the dementor.

"EXPECTO PATRONUM!" You shouted, focussing as hard as you could on (h/m). To your suprise, a (y/p) shot out of the end of your wand, heading straight at the dementor, which turned and fled.

"(Y/N)!" Sam and Dean cried as you collapsed to the floor.

"Here! Move, move!" The brothers parted to make way for Madame Rosmerta. "Ok, ok. Here, eat this." She pulled you into a sitting position and handed you the chocolate which you accepted readily.

"Has it gone?" Dean asked you.

"No, it always comes back. I don't know why." Rosmerta replied, shaking her head. "It's ruined business all over the village."

Sam and Dean turned to each other, nodding slightly.

"No guys, a dementor would have a field day with you two."

"She has got a point Dean. What memories can we use that will be happy enough?" Sam turned to Dean.

"Well, that first time you came back from the dead? Any of our childhood weekends at Bobby's? That Christmas you gave me the samulet? Finding Cas...." Dean tried to list more but fell quiet, mumbling the last one. You winked at Sam when Dean mentioned Cas.

"They're good for you. My happiest is probably leaving home and running to Stanford... Meeting Jess..." Sam's face slightly dropped as Dean winced at the mention of Sam's disappearing act.

"They just need to be strong, not necessarily entirely happy." You helped out. The boys nodded.

"Let's go gank this SOB!"

****

The brothers spent a couple of days brushing up on their knowledge, with you correcting them if they got something wrong.

While they were doing this, you went round Hogsmeade, refusing to miss any opportunities to learn spells. This was your dream after all. Stupid dementor ruining it. After talking with most of the residents (students weren't allowed down to the village since the appearance of the dementor), you learnt many were depressed and had lost will. Understandable as the dementor had been around for a few months, and most didn't know the Patronus charm.

You decided to act.

"Okay! I'm going to teach you the Patronus charm." You shouted to the group. Everyone was crowded into The Three Broomsticks, now silent and staring at the girl stood on the table in front of them.

"I need you to focus on your happiest and strongest memory, okay? Take a few minutes if you need to." You began, watching as many of the residents closed their eyes clearly needing a while to find one through the mirk the dementor had bought. Once everyone had reopened their eyes, you carried on.

"Now, the words are 'expecto patronum'. Practice saying it, with force, and without wands to start with." Chants of 'expecto patronum' began. "Now focus on your memory, at the same time." People began shutting their eyes again as they focussed on the memory.

"Ready?" I few nods, but everyone was refocused on you.

"Everyone, spread out! And wands at the ready, okay?" You paused as people moved to find a little area of their own or in pairs and threes.

"Remember, 'expecto patronum' and focus on your memory!" The chants began again, a few wisps of blue came from a few wands. "Keep going! Really focus on the memory! If that one isn't working, find another. It needs to be strong, powerful." This time almost everyone got a strong blue light from their wands. "Very good! Keep at it, if you start to feel weak, eat some chocolate."

You jumped down from the table, and walked around the room, watching and directing people as time drew on. Sam and Dean walked in, dragging the attention of a few people, but most were focussed on the charm and many had created a full patronus.

"Wow. You're doing well in here, (Y/N)!" Sam whispered to you.

"Thank you, Sam. I figured they need to know what to do if one comes back." The brothers nodded. You had taught them the spell the day earlier.

"You ready, (Y/N)?" Dean asked, casting his eyes around the room.

"Yep. One moment." You called for everyone to stop, and that the lesson was over. " Keep practicing, okay guys. There's chocolate over here, everyone take a bit." With that, you, Sam and Dean left, heading towards the Shrieking Shack where you had agreed to start.

****

It had gone very well. Using the three patronuses, you had cornered the dementor, before chasing it out of the village. You heard a clock chime midnight, as Gabriel reappeared. Within a moment you were back in the bunker.

"Thanks for an amazing birthday, Gabe!" You smiled and hugged the archangel, kissing him on the cheek before he left.

"Well, it was interesting." Dean finally said, before you headed to your rooms, texting Charlie on the way. You knew what you were doing for Christmas anyway.