A tragedy had wrapped its nasty claws around Hogwarts, snuffing all the hope and light out of it. Darkness pervaded around like a slithering snake, taking over everything and everyone. The Hogwarts headmaster, Albus Dumbledore, was dead. He was killed right there, in their school, by one of their own. There was a traitor in their midst, and Y/N knew who it was.

She pushed through the crowd that had formed at the base of the Astronomy tower where Dumbledore had fallen. Tears pricked her eyes, but she had to keep a level mind right now. She would have time to grieve for Dumbledore later, when she was alone with her friends. Right now, she had to find Draco Malfoy.

The frigid air was suddenly cut off once she shut the door behind her. Most of her classmates and professors were outside, mourning the death of their beloved headmaster. But her brother was nowhere to be found. He should have been with the rest of the Slytherin students; he wasn't. That meant that he had something to do with Dumbledore's death. She just knew it like she knew that the sky was blue. He had been recruited into the Death Eaters by their father, Lucius Malfoy. This must've been what his mission was: killing Albus Dumbledore.

Y/N hadn't been in the dungeons in a long time. When her and Draco first became students here, she would sneak into the Slytherin dorms because she was terrified of being without her big brother. As time went on, she ended up making friends with Harry Potter, Hermione Granger, and Ron Weasley. They were like the family she wished she had. Lucius Malfoy was the person that drove Y/N away from the rest of her family. He controlled her mother and brother, but she wouldn't let him control her. 

Her family hated that she was friends with Harry Potter. Even Draco and her fought about her being friends with Harry. He always told her that Harry only wanted to be her friend because she was pretty smart. Draco tried to forbid her from spending time with them, but she never listened to him. She didn't want to betray Harry and Ron and Hermione by listening to Draco.

Y/N approached the stone wall that doubled as the door to the Slytherin dorms. She cursed herself for not asking Draco what the password was. Each year before, he would always tell her just in case she needed to talk to him or something like that. Lately, though, it felt like there was a wedge between the two of them that kept driving them farther and farther apart from each other. It was sad that they weren't close like they used to be.

"Y/N, what are you doing here?"

Y/N whirled around and saw Draco standing behind her. His eyes were crinkled and his brow was furrowed. When she took a step closer to him, she noticed that his hands were shaking. 

"Where were you?" she asked him instead. "Do you know what happened?"

"Know what?" he asked. 

She could tell that he was trying to lie to her, but she knew better than to trust him. "I can't believe it." Y/N swallowed hard. Her worst fears had come true. Draco was becoming the monster that their father was making him be. "I can't believe that you killed Dumbledore."

"What? No, I didn't kill him," Draco hissed. His eyes darted around the two of them. "I didn't kill him. I promise."

"You've lied to me before," she said, throwing her hands up into the air, "so why should I believe you now, you bloody traitor?"

"Y/N!" Draco snapped, grabbing onto her wrists. He shoved her toward the Slytherin common room door, muttering the password. He pushed her in before shutting the door behind them. "You need to believe me. I didn't kill Dumbledore."

"Sure," Y/N said, rolling her eyes. "Just like you didn't let those people in earlier today."

"How do you know about that?" Draco looked taken aback. 

"I followed you." Y/N held out her wand in front of her, blocking him from getting any closer. His eyes widened. "I swear, Draco, if you take one more step, I will blast you through this wall."

"I'm not going to hurt you," Draco said quickly. He raised his hands above his head. "I was trying to find you so we can run away."

"Running away is for cowards," Y/N sneered. "What, you can't stay here and face the consequences for your crimes? You can't go to Azkaban? You won't be alone. Dad's there."

"No, he's not," Draco said hastily. "That's besides the point. I want to run away to start a new life."

"A new life won't erase what happened here," Y/N said. "I won't forgot. I will never forget." For a second, she wondered if he hadn't actually killed Dumbledore. He had always been her best friend, up until their time at Hogwarts. He was always the one who protected her from their father. "I'm not coming with you. But if you do end up running away, good luck. Maybe we will see each other in another life."

With that, Y/N brushed past her brother. He didn't even try to stop her from running away from him.

The cold air that had permeated through the open doors chilled her right to the bone, but she didn't mind. It was better to feel the coldness and be numb to her emotions than to cry under the warmth of the sun. The passageways blurred past her as she ran toward the light at the end of her tunnel - her friends. 

Y/N burst outside, near where the dead body of their beloved headmaster was. The people were still there, which meant that Harry, Ron, and Hermione would be there. Hopefully. She pushed through the crowd, searching for her three friends. She caught sight of the familiar red hair of Ginny, so she stopped walking for a second.

"Oh, good, Y/N," Ginny said with a breath of relief. "Harry, Ron, and Hermione went inside to find you. No one knew where you went, and they were worried."

"Do you know where they went to first?" Y/N asked quickly.

"Harry told me that they were going to check Dumbledore's office first."

"Thanks."

Y/N turned around and ran back inside. She took the stairs two at a time, trying to get to Dumbledore's office as quick as she could. She knew that Harry would take this the hardest out of the four of them; him and Dumbledore had a special bond. However, Y/N still took it hard because she spent some time with Dumbledore, too. 

The door to the Dumbledore's office was wide open, so she ran right through it. Harry, Ron, and Hermione stood in the center of his office, talking quickly with each other.

"Guys!" Y/N said. 

Hermione turned around. "Y/N! Where were you?"

As Hermione pulled Y/N into a hug, Y/N explained to them that she had to find Draco. She didn't tell them that he wanted to run away, though. Y/N let go of Hermione and walked over to Harry. She wrapped her arms around him, pulling him into a hug, too. His face was red and blotchy. She really wouldn't have been able to tell that he was upset, yet she still knew. She looked the same when she got upset.

"Hey, Y/N, Harry, I think you two should look at this," Hermione said from behind them. 

Y/N pulled away from the embrace with Harry and turned toward Hermione and Ron. The two of them were peering at something. Y/N walked over to them and touched Ron's arm. He gave her a tight-lipped smile. 

"What is that?" Harry asked, drawing Y/N's attention back to whatever they were looking at.

She scanned the word on the small piece of paper. With each word, her heart fell farther and farther down. She glanced at Harry to see him watching her. "What does this mean?" she asked them.

"The only way to know what it means is to use the pensieve," Hermione said softly. 

She threw off the cloth that was covering the pensieve, revealing a shallow stone basin. Strange runes and symbols were carved into it. A cloudy liquid swirled around the basin. Hermione slowly let the memory fall into the pensieve.

"You dip your head into the liquid," Harry explained quietly to her. He must have seen the confused look on her face. "I'm sure we both can fit our heads in here."

Harry proceeded to go first. He placed his head in the pensieve without a second thought. Y/N glanced at Hermione who gave her an encouraging nod. She took a deep breath and plunged her head into the liquid. Everything went dark for a second before getting very bright. 

Y/N had to shield her eyes from the intense sunlight that drifted through the window on the wall to her right. The house she was standing in felt like it was filled with love and warmth. She glanced around and saw a man. He was perched precariously on the table, screwing in a lightbulb into the chandelier. He looked so much like Harry. He even had that same mischievous grin that Harry had. 

"Oh, James!" a sing-songy voice called out. "It's your turn to change Harry's diaper?"

James clambered down from the table and grinned up at his handiwork. He wiped his hands against each other before saying, "Lily, I did it last time on Y/N. You should have seen her diaper."

The woman - Lily - entered the dining room with a younger looking Dumbledore. She was also holding two babies in both of her arms. Dumbledore had an easy smile on his face. "I see that I came at the wrong time," he said with a chuckle deep in his throat. 

"No, no, it's fine," Lily said. She handed one of the babies to James and poked his chest. "Your turn."

James stuck out his tongue at Lily and the other baby in her arms. "Who ever let us have Y/N after Harry? This is difficult."

"Difficult, yes," Lily agreed. She smiled up at her husband. "But they are so loved." James and Lily gazed down at their two children with love in their eyes.

"Harry and Y/N Potter, you two will always be loved," James said softly. "No matter what your Uncle Sirius tells you, we love you both more than anything in this world."

Y/N couldn't believe what she was hearing. Her vision went dark again, and when she blinked, she was back in Dumbledore's office. Harry already had his head out of the pensieve, and he was staring at her.

"I can't -" he began to say.

"That - That was - I never expected that," Y/N finished. 

"What happened?" Ron asked the two of them.

"We - we are brother and sister," Harry said, gesturing between him and Y/N. "She's my little sister."

Hermione gasped in surprise. "Is that why you have a scar on your forehead, too?" she asked Y/N.

"It has to be," Y/N breathed out. "Draco told me it was because I fell down and knocked my head against the counter at home." She swallowed hard. "Why was I with the Malfoy's if I am your sister?"

"I have no idea," Harry said softly. A bright smile appeared on his face, and he threw himself into Y/N's arms. "I have a sister! This is so much better than the Dursley's. I finally have someone who actually loves me."

Y/N smiled. "No wonder I didn't feel like I belonged with the Malfoy's."

The two of them pulled away from each other. Harry held her at arms length and said, "I knew you had the same chin as me."

"You're just making that up to make you seem smart," Y/N teased. 

"Maybe I am." Harry grew serious and said, "I know we just found out that we're siblings, but I don't think you want to go back home with Draco."

Y/N sucked in a breath. She still loved Draco like a brother. He was a good guy if you didn't dwell on what he did tonight and what he did to Harry. He was the only thing that she would've gone back for. 

"Not really," she said to him. "I can't, anyway. He ran away."

"Well, you can stay with me," Harry said with a nod. He glanced at both of their friends and said, "I hope you guys will stay with us, too."

"Of course," Ron said immediately. 

"We're always going to be with you guys," Hermione told them.

"We need to figure out how to defeat the Dark Lord," Harry said to each of them. 

"He took our parents away from us," Y/N said with a determined look. "We will do whatever we can to defeat the Dark Lord. Together."

"Together, yes. That sounds perfect."