Lily woke up suddenly. It was about a week into the summer holidays after her second year at Hogwarts.
She didn't know what had woken her until she heard the noise again: a faint, rapid tapping at her bedroom window.
She got out of bed and peered out the window. She couldn't see anything in the darkness. She opened the window and look around outside.
"Lily!" Severus whispered.
She started and hit her head against the window frame.
"Merlin, Sev, you scared me."
"Sorry."
"What are you doing here?"
"Let me in?" He sounded frantic, like he desperately needed her to say yes.
Lily helped him climb through the window.
"What are you doing here?" she asked again once Severus was inside.
"Can I stay here? Just until morning."
"What happened?"
"Nothing. Nothing happened."
Lily turned on the light next to her bed. They both blinked and squinted in the sudden light. As her eyes adjusted, she could see that something had definitely happened.
Severus had a series of bright red marks on his face; some on them were already darkening to black and blue. His shirt was torn open at the shoulder, revealing scratch marks and more fresh bruises.
Severus looked at the floor and said, "Please let me stay here."
"Severus, what happened?"
He wouldn't look at her. "Please," he said.
"You can stay. I'll just tell my parents."
"No! No, they'll make me go. They'll call my parents."
"No, they won't."
"Yes, they will." He looked her in the eye now. He stared at her wide-eyed, drawing shallow panicked breathes, looking absolutely terrified.
Lily hesitated. If her mother came in to check on her and Severus was there, she would be furious. Lily weighed the outcomes. She decided that the punishment she would get for having Severus there after hours wouldn't be nearly as bad as what might happen to Severus if he went home.
"Fine," she said, "I won't tell them."
"Thank you."
"Here. Let me fix your face."