Yelena was from Russia. She had spent her early childhood in poorly built orphanages and the bleak Red Room, shivering in her sleep and wearing all her clothes to bed. She remembered the ice cold wind that blew through the cracks of the building, the ice that formed in the sink if someone left the tap running overnight, the snow that piled up outside and blocked the door if it wasn't shoveled away regularly.

Yelena was used to the cold, or so she thought. She was learning, however, that Scottish weather was a completely different type of cold. This was a damp cold that settled in her bones, a relentless rain and wind and sleet that was just pure torture.

Now that it was November, it never seemed to stop raining. Yelena sat by the window of the Slytherin common room, her nose pressed to the glass as she stared out at the dark rainy sky. Sighing loudly, she turned towards her sister, her cheek now smashed against the window pane.

"I'm bored." She whined, her voice muffled.

Natasha rolled her eyes but didn't look up from her parchment as she continued writing.

"Lena, I'm trying to study. Why don't you finish your homework?"

Yelena groaned and peeled her cheek from the window. "I'm sick of studying! Let's do something!"

"I have this essay to write for Charms. I'll play chess with you after, but I need to finish this first. Why don't you go find Wanda?"

"She's at Gobstones club. I don't like Gobstones!"

Natasha sighed, dipping her quill in ink. "I really have to focus, Lena, please. Just - find something to do. I'll be done in an hour."

Yelena sighed loudly and stood up from the sofa. "Fine! I'll go find someone else to hang out with then."

"Okay." Natasha said absentmindedly, her focus already on her essay.

Yelena left the common room with a huff. Why was everyone suddenly busy? Natasha was studying, Wanda was at Gobstones club, Pietro had gone with her, Vision was home for the weekend, Loki was probably in the kitchens with Nebula, and even Clint was studying in his common room.

She wandered around the halls for a little bit, looking for anything to do, but it soon seemed that she would be forced to study, after all. She turned around and headed back towards the common room, walking past the kitchens. Just as she passed the statue of the one-eyed witch, however, she heard a sound.

Stopping, she turned towards the statue, and then she heard it again. It was like a low growl, almost like that of a dog. She moved towards the statue, and pulled out her wand. She pointed it at the statue, moving slowly towards it as the growling continued.

"Dissendium!"

The statue slid aside to reveal the secret passageway that Natasha had told her about. Yelena moved closer, and cautiously stepped in the tunnel, keeping a firm grip on her wand.

"Hello?"

The snarling grew louder, and Yelena moved towards the direction of the sound, her heart thumping in her chest. As she took another step, she brushed against something in the dark. She jumped backward and gasped as she spotted a pair of eyes blinking at her.

"Who's there?" She cried, backing into the wall. "Who are you?"

She rummaged around in the pocket of her robes, looking for her Muggle flashlight. Natasha always made fun of her for carrying it, but Yelena couldn't cast Lumos yet, so it was handy to have. She clicked the button on the side of the flashlight and a faint light illuminated the tunnel.

"Ahhhh!" She dropped her flashlight in shock.

Towering over her in the dark was a massive wolf-like creature. It was huge, almost twice Yelena's size, with green-gray fur and glittering black eyes. Snarling, the creature swiped at her with its claws, and Yelena narrowly missed being mauled as she quickly ducked.

"Shit!" She grabbed her flashlight from the floor and backed away from the animal, holding up her hands.

The creature moved in her direction, growling as it closed the distance between them. Yelena wiped her sweaty hands on her robes and tried to keep them from trembling as she slowly took another step backward. Raising her wand, she wracked her brain for a spell that would help her in this situation.

"Incarcerous!" She cried, and ropes shot out of her wand, tying the wolf's huge legs together. The creature fell to the ground with a thud, and let out a loud howl. Yelena raised her wand again, and aimed it at the creature.

"Petrificus Totalus!"

The wolf now lay motionless on the floor, its dark eyes staring at her accusingly. Yelena let out a relieved breath and sank to the floor, clutching her wand tightly. Now that the immediate danger had passed, she took a closer look at the creature.

It was clear that this was no ordinary wolf, but what could it be? Suddenly, she remembered something her father had once told her about work he had done at the Ministry of Magic, tracking werewolves. His description of werewolves seemed to fit this creature exactly.

Someone at Hogwarts was a werewolf.

Yelena remembered Alexei mentioning that it took hours before a werewolf reverted to their human state, so she sat in the tunnel and waited, watching the wolf with caution. As the hours passed by, she watched for any signs that the werewolf would transform, her wand at the ready. Finally, at around two in the morning, she saw the creature start to twitch, his wolfish features shrinking as the fur rapidly disappeared.

Yelena reversed the spell, and the werewolf writhed on the floor of the tunnel as he transformed, his face screwed up in pain as he took on the form of a skinny teenage boy. Once the transformation was complete, he seemed to realize where he was, and his eyes grew wide with fear upon seeing Yelena.

"Who are you? Please tell me I didn't hurt you! I - where are my clothes? I always leave them here when I transform!"

Yelena raised her hands in a placating manner, trying to appear non-threatening.

"It's okay, you didn't hurt me. I was able to petrify you. I'm not sure where your clothes are, but you can borrow my cloak if you want?"

She took off her cloak and offered it to him. He took it with shaking hands, curling in on himself after he put it on.

"I'm so sorry! Usually no one comes back here, I would never have come here to transform if I knew you were here!"

"It's okay." Yelena said again.

"I can't control it! I don't want to hurt people, but I can't stop the other guy from doing what he wants during the full moon!" The boy said, his voice trembling.

"I know. I'm sorry I came back here, I didn't know this was your spot."

Yelena sat back down on the tunnel floor and put her wand back in the pocket of her robes.

"My name's Yelena. Yelena Belova. What's yours?"

There was a moment of silence as the boy looked at her, his hands curled tightly around Yelena's cloak.

"Bruce Banner." He replied tremulously.

"Nice to meet you, Bruce. What House are you in? I'm in Slytherin, first year."

"Ravenclaw. Sixth year."

"Cool!" Yelena said, offering him a smile. "My sister Natasha's in sixth year, she's a Slytherin too."

"Natasha? Natasha Romanova?" Bruce asked, and Yelena nodded.

"Yes. Do you know her?"

Bruce shrugged awkwardly. "I mean, we were friends, have been since first year, but lately - lately I don't think she wants to be friends anymore. We hang out with the rest of the group, but it hasn't been the same. I didn't know she had a sister."

"What happened?" Yelena asked curiously. She couldn't remember her sister mentioning a friend called Bruce, although to be fair Natasha's friend group was pretty big. Clint came over every school holiday and practically lived with them, but Yelena didn't really know the rest of Natasha's friends, except for maybe Steve, who came over occasionally during the holidays.

Bruce frowned. "Last year, we sort of - I don't know, we sort of dated for a bit. Not that long, just a few months in the spring. But then we all went home for the summer, and I - well, I don't have an owl, and my parents kept me away from people all the time because they were worried about my, you know, condition getting worse and I couldn't send any letters or come visit. We always meet up with the whole group every summer, and I couldn't this year. The next time I saw her, in class, she told me we were done. I get it, I do, but I hoped we could still be friends, even if she doesn't know the reason I ignored her all summer. I can't tell her about this, you know. None of the group knows."

Bruce sighed heavily and gripped Yelena's cloak tighter.

"Wow. That is a sad story, Bruce Banner." Yelena said. "But why would you not just tell your friends you are a werewolf? Natasha would not be angry with you if she knew the reason you didn't visit and didn't write."

"I guess I'm just afraid." Bruce admitted. "I don't want my friends to think I'm a freak. I don't want to put them at risk."

Yelena rolled her eyes. "That's just stupid. If people don't accept you for who you are then they're not real friends. And my sister is a real friend, I promise. You should tell her."

"You're probably right." Bruce admitted, smiling wanly.

"I'm always right." Yelena said smugly.

She pushed herself up off the floor with a groan, and held a hand out to Bruce. "Why don't we leave this depressing tunnel and get some sleep? And tomorrow, we will go find my sister and your other friends and you will tell them your secret. Deal?"

Bruce hesitated, but took her hand and stood up.

"Deal."