Snape sat at his desk, staring at the wall in the lamplight. Miss Renner's lesson was still on his mind. Well, Miss Renner in general was. Snape was unsure of how anyone could hate that child. She was kind and compassionate, but also determined and unyielding...much the way Lily had been...for what felt like the millionth time since the beginning of the school year, Snape had to close his eyes to ward off the wave of pain that crashed into him when he thought of Lily. If I'm ever so undeservedly fortunate as to find someone like Lily again, he thought determinedly, I will not make the same mistakes. Not for the world. I swear on Lily's memory.

But I have found someone like Lily, he thought suddenly. Miss Renner. Cassandra. She's very much like Lily. The unexpected thought caught him off guard. Since when had he started comparing his student to the woman he loved? The woman who had left him, a very long time ago, with a gaping void that nothing thus far had managed to fill. Would it ever be filled? Today in the dungeon, experiencing the magic that Cassandra had produced, had felt so much like the times he had once spent with Lily. Could anything about Cassandra be a substitute for what he had lost?

"Severus..."

Snape shot to his feet so fast his chair almost toppled. All thoughts of Cassandra were gone. Had he imagined that voice? Because as surely as he knew his own name, he knew that voice belonged to Lily Evans. Was he losing his mind? He waited a moment, and when nothing happened, he hesitantly dismissed the sound as the product of an overworked mind. Then it came again.

"Severus, please don't ignore me."

He whirled around towards the spot he thought the voice must be coming from, eyes frantic, looking for whatever was playing this cruel joke on him. He froze.

There, in the corner of Snape's office, stood the spirit of Lily Potter, smiling at him.

Trembling, Snape fell to his knees. His dark eyes were instantly welling with tears that he couldn't stop. The silver image of the woman he loved came a few steps closer with a small, sad laugh. "Severus, is my loss still so fresh for you?"

"Ten years..." he croaked, disregarding the tears cascading down his cheeks. "You had to have known, Lily, how hard it was. Why didn't you come sooner? I've needed you so many times..."

Her expression became regretful. "I'm sorry, Severus. I couldn't. My spirit isn't free, I could only pick one person to attach to after that night. I had to stay with my son, and until he came to Hogwarts, I couldn't see anyone at Hogwarts. But now that he's here, I'm close enough to see you." She smiled again.

Snape was still shaking. "Lily...Lily, I'm so sorry...I messed up so badly...I never wanted for you to be mad at me. I loved you too much, and I couldn't see what I was doing. I'm so sorry..."

"Severus, all is forgiven. It always was, you know. I was never so mad at you that I couldn't forgive you." Snape looked down at the ground, knowing he didn't deserve to be forgiven for what he'd done. "How can I repay you? How can I make amends? Say anything, I'll do it. What can I do?"

Lily looked compassionately at him, then came closer. She slowly knelt down on the floor facing Snape. He looked up at her with tears in his eyes. She leaned forward and whispered, "To prove your love for me...to make amends...move on, Severus. Find another love." His look became incredulous. "Of all the things you could ask me to do," he said shakily, "you pick the one which I cannot. How can you want this?"

"Because your love does me no good, and it does you no good. I have a husband and a son, and they are my responsibility. I cannot return your love. And you...you can't live like this forever. Honestly I'm amazed you made it these ten years."

"Live like what?"

"Alone, Severus." Lily had tears in her eyes too now. "You're so secluded from the world. You hardly talk to the other teachers, you interact as little as possible with the students, and Dumbledore is the only one you trust. You need to live more."

Snape was astonished. "How do you know all that about me?" he said.

Lily smiled. "I've been at Hogwarts since the beginning of the year. This isn't the first time I've seen you." She stood up. "I have to go, Severus. I've been away from Harry too long." She began to move towards the wall.

"Wait!" cried Snape. She paused and looked at him. He looked back at her desperately. "How do I move on?" he whispered. "I don't know how."

"I'll help you," she said softly. "After all, help will always be given at Hogwarts to those who ask for it." She smiled. "For now, continue with the girl's - Cassandra? - with Cassandra's lessons. They will be good for both of you. They will teach both of you to open up, and who knows? You might even find you like her." She backed away slowly, and when she reached the wall, she said, "Goodnight, Severus." Then she disappeared.

Snape stayed kneeling on the floor for a while longer, then realized where he was and took himself off to his room. It wasn't until later, after his thoughts had calmed some, that he remembered his words from earlier. "Kind and compassionate, determined and unyielding...Very much like Lily..." and "If I ever meet someone like Lily again, I won't make the same mistakes." Then Lily's words came back to him - "Who knows? You might even find you like her." Snape thought that he might indeed find that he liked Cassandra, although maybe not the same way Lily was thinking.