A/N: While I didn't necessarily specify what year this takes place, it is just shortly after Lily would've been hanging around with James and company. Hence why Marlene didn't know "the big secret" yet.

Harry Potter Halloween Collection Prompts: (feeling) panic; (location) The Shrieking Shack

Halloween night. James, Sirius, Remus, Peter, and Marlene would usually be at the Halloween feast at Hogwarts. Except that Sirius had dared the others that they couldn't last the night in the Shrieking Shack. The other three boys had immediately accepted the challenge. Marlene had been hesitant at first, but Sirius had finally goaded her into it. Lily flat out refused, so Marlene would be the only girl going.

"How in the world are we getting past the Whomping Willow?" Marlene asked skeptically as they reached the tree in question. It began waving wildly as they got close.

"Stand back, McKinnon," Sirius said, taking out his wand and pointing it at the tree. He muttered something under his breath, and the tree stopped moving. "Come on, this way." The other four followed him to the base of the tree, where a hole leading into a passage was visible.

"How do you know all of these secret passages anyway?" Marlene asked as they walked through the passage, illuminated only by the light of Sirius's wand in front of them.

"If we told you, we'd have to kill you," Remus said seriously.

"Yep, top secret stuff," Peter added.

"Ok, fine," Marlene said, rolling her eyes. She was sure that if she could see their faces better that they were probably smiling slyly. "Don't tell me. Keep your little secrets." That's funny, she thought to herself. I don't remember Peter actually following us in here... Shrugging, she decided that maybe she was just remembering incorrectly and put it out of her mind.

"Alright, here we are." Looking around, Marlene could see they were in what looked like a basement. Cobwebs and dirt on the walls were illuminated by the wand light. A set of rickety stairs led up to a door. He motioned toward the stairs. "After you, Marlene."

When she stepped through the door at the top of the stairs, she saw total wreckage. Broken furniture and torn fabric lay everywhere. The windows were all boarded up, but there were a few small gaps here and there, letting in some light from the half-full moon. They appeared to be in the main entrance of the house. There was a set of stairs leading to the second story and several doors to other rooms. Some of the doors were partly open and hanging precariously off their hinges. Dust and cobwebs covered everything.

"Pretty scary, huh?" James asked. "They call it the most haunted place in Britain. Think you can last the night?"

"Of course I can," Marlene said indignantly. She looked around the room. "Hey, where's Sirius?"

Remus also glanced around, looking slightly worried. "He was right behind me, he was the last one up. I'm sure he came through the door."

"Come on, Sirius," James said loudly. "The ghosts are supposed to freak us out, not you." There was no answer from Sirius. All they heard were the floorboards creaking under their weight and the wind blowing outside.

"Oh, he's here somewhere," James said, opening a door and sticking his head through the doorway. "Get out here, you - AAAAAAARGHHHHH!" James screamed and was suddenly yanked through the doorway, the door slamming behind him.

Peter ran towards the door, but Remus stopped him. "No Pete, don't! It's too late for him. The ghost got him." Remus was shaking as he held his friend back, an expression of horror on his face as he stared at the door.

"We've got to do something!" Marlene shouted. "What if it got Sirius too?" Her heart was thudding in her chest, her breathing shallow. She couldn't bear the thought of anything happening to him. He had become one of her best friends.

"We...we can't do anything." Peter was sobbing. "They say once the ghost that lives here decides it wants you dead, you can't escape. The only way they say you can get out is to survive until sunrise." He buried his face in his hands.

They heard an unearthly shriek from above them and a loud thud. Remus and Marlene left a trembling Peter behind and walked to the foot of the stairs, looking up to the second floor landing. "What do you suppose that was?" Marlene whispered.

"I'm not sure," Remus muttered. "I don't think it was friendly though. Pete, come on -" He stopped midsentence and tapped Marlene on the shoulder. She turned to look and nearly screamed.

Peter lay in a heap on the floor with a large black dog looming over him. It was the most frightening dog she'd ever seen. It's fur was matted and dirty, it was baring large white teeth, and there appeared to be blood on it's mouth.

"Don't. Move." Remus stood frozen next to her, looking absolutely terrified. Marlene was barely breathing or blinking. She didn't think she'd ever been more scared in all her life. They watched as the dog dragged the unconscious (and hopefully not dead) Peter away by his ankle into another room.

"Oh Merlin, what was that thing?" Marlene whispered. "It looked like a dog, but -"

"It was a grim," Remus said, voice trembling. "We have to get out of here. Those things don't normally hurt people, they just warn of impending doom. Whatever nasty spirit lives here must be using that thing to actually hurt anyone who comes across this place." She could see that he was just as frightened as she was.

He tried opening the front door with no success. It was barricaded too well. He tried the door that they had come through, but it was now unable to be opened. "It's not going to let us leave now." Remus pounded the door in frustration. "OPEN THE DOOR!" he shouted. "PLEASE LET US OUT!" He tried other doors; some opened, but only partially and not enough for them to squeeze through, while others wouldn't open at all.

The last door he tried opened fully. "Finally. Marlene -" The dog jumped on him before he could finish his sentence and dragged him by the collar through the door. As before, it slammed shut behind the grim and its victim.

Marlene screamed. She was alone now. No one to save her. Having someone else there might've made things a little easier. Trembling and sobbing, she collapsed onto the floor. What was she to do now? If Peter had been correct, her only hope was to survive until sunrise. Considering the others had all been taken within a half hour of being in the house, what chance did she stand?

She heard growling and looked up. The dog stood quite close to her, it's teeth bared. Panicking, Marlene backed up until she found herself in a corner. The dog followed her slowly, growling the entire time.

"No no no no," Marlene sobbed. "Please, I don't want to die. Please..." She covered her head with her arms, waiting for the dog to strike, to kill her. It would all be over in a moment, she could stop panicking now...

Except that something felt different suddenly. No, something sounded different. The dog wasn't growling now. It was laughing. Dogs don't laugh. This thought broke through her terror and she slowly uncovered her head.

Sirius stood before her, doubled over, laughing. Remus, James, and Peter were behind him, laughing as well.

"You should've seen your face!" Sirius gasped. He collapsed on the floor, laughing even harder.

"What...what's...I don't understand." Marlene's panic had been replaced by total bewilderment. Hadn't she seen James, Peter, and Remus get dragged off by the dog? And Sirius had disappeared the moment they'd entered the house.

It took a few moments for the boys to calm down enough to explain everything to her. They explained Remus's lycanthropy, the ability of the other three to turn into Animagi, and the purpose for the Shrieking Shack.

Marlene's head was spinning by the time they'd finished. "So, you've mapped out all the passageways leading out of the school -"

"Correct." Sirius nodded.

"Remus is a werewolf and you all can turn into other animals, to keep him company and bring no harm to yourselves -"

"Yep."

"Peter was in his rat form and stood on the knot to let us past the Whomping Willow?"

"Mhm."

"And you were the dog?"

"Yes'm."

"Everyone else was sneaking around under James's invisibility cloak after they'd been taken, making noises and slamming doors?"

"As planned."

"And since it's Halloween, you decided to scare the living daylights out of me to introduce me to all of this madness?"

"Yep." Sirius smiled. "Did it work?" The smile disappeared from his face when Marlene slapped him. The sound echoed through the room. They all looked at her, shocked.

"You bastards!" she screamed. "You're all mental! You could've just told me!" She stood up and stormed to the basement door, which unsurprisingly opened this time. "You stay away from me!" She slammed the door behind her.

She was so furious she didn't even remember making it all the way through the passage. When she came through the tree once more and found it not trying to pummel her, she shouted over her shoulder, "Thanks a lot, you stupid rat!"

She stormed across the grounds and was halfway back to the castle when she heard Sirius calling after her.

"Marlene, please wait!"

She stopped and turned, waiting with her arms crossed. "What the hell do you want?" she asked when he got closer.

"I want to apologize, if you'll let me. I know we could've handled that better, but please don't be mad at them. It was my idea." He reached for her, but she jerked away.

"Don't touch me! You thought it would be funny? What kind of a friend are you?"

"I thought you might have fun with it," he admitted. "You did tell me you like to be scared, so I thought that after you found out it was all a prank, you'd have a good laugh about it with us."

"Yes, I do like to be scared. But don't you ever make me think you're dead as a prank. It's not funny." She turned away, trying not to cry. "I thought something had happened to you. I thought I was never going to see you again."

They stood in silence for so long that Marlene wondered if he'd left her alone. He spoke just as she was about to turn around to see if he was still there. "I'm sorry. I didn't think -"

"That was obvious," she interjected. She didn't resist when he turned her to face him.

"Can you forgive me?" He looked at her pleadingly. "Please?"

She sighed. "Yes. Eventually. Just leave me alone right now, ok?" She walked away without waiting for an answer. Most of her anger had subsided, but she was still mad enough to slap him again if he gave her the opportunity. Best to just keep my distance for now, she thought.

A week later, she joined him after breakfast and walked with him to Charms. They walked in silence, he too afraid to say something that might drive her away again, and she trying to think of the right thing to say.

"You know," she finally said, just before they entered the classroom, "I have to admit, aside from faking your death, that was a brilliant prank. Thanks for the scare. Apology accepted. Oh, and don't do it again."

"Of course." He smiled. Everything was right again.