Maria was frozen on the spot.
"Oh god. I'm dreaming."
Bartemius smiled ruefully.
"This isn't happening. It can't be happening. You're dead. I'm dreaming."
"Maria..."
Maria now had an odd look on her face, and odd fixed look. Her pale grey eyes stared straight through Barty.
"I'll just go back to bed now. I'm dreaming."
"Maria," Barty said, moving out from behind her desk. Maria turned, walked back to her room, eyes tightly closed and fists clenched.
"Maria Celeste Sinistra, you aren't dreaming."
"I am."
"You aren't."
"Okay, I'm not. After all, I'm hardly crazy enough to argue with myself, am I?"
"Oh, of course not," Barty said, half-smiling.
Maria looked up at the ceiling.
"I think I must've gone crazy."
"You're not crazy."
"You were in Azkaban. You died."
"I was in Azkaban. I escaped."
"You died."
"My mother died."
"Your mother died of grief when you did. I nearly did too," Maria said, bitterly.
"We swapped. Mother... I don't know how she did it. I just woke up one day, and I was being pulled out... I barely knew what was happening."
"Yeah, because my mind can't be bothered explaining it properly to myself. So if you weren't in Azkaban, where were you?"
"Home. If you can call it that."
"And you didn't tell me? You were alive and you didn't tell me."
"My father is not a generous man, Maria. I'm alive because my mother entered Azkaban in my place. My father saved me for her, but he wasn't going to make me feel grateful."
Maria smiled sadly.
"I never did like your father."
They stood in silence, a moment, a minute." Then Maria looked up.
"Why are you here?" she asked.
"I escaped."
"Oh," Maria said, biting her lip. "Will I ever see you again, after this."
Barty smiled, sadly.
"Perhaps."
Then again, they were silent. Barty walked up to Maria, took her hand. Maria followed him automatically. She knew exactly where they were going.
They spent the rest of the night staring up into the stars Maria knew so well.
"You teach Astronomy now, then. Aren't you glad then, I dragged you out all those nights to watch them."
"Only for you Barty."
Barty leant over to squeeze Maria's hand. Suddenly, her eyes were filled with tears. Her voice choked.
"I miss you, Barty. More than anything. Why'd you have to go and do it? Wasn't I enough for you? Did you have to turn to him?"
Barty said nothing. He let go of Maria's hand though, and stood up.
"Don't go," she said, wistful. "Don't leave me, don't leave me for him."
Barty looked away, he closed his eyes tight.
Maria sighed.
"That's okay. I know you can't. Just... remember me. Barty?"
Barty leant down, and kissed Maria on the forehead. She smiled dreamily.
"I love you, Barty," she said.
"I love you too," he said. "I'm sorry."

-----

I wrote this on a whim. I think it's kind of sweet.
I borrowed Sinistra's name from the H.M.S. Crouching Death Eater Hidden Astronomist. Because I think it's a nice pair.
Finally, I'd like to say these characters aren't mine, their J.K. Rowling's, despite my claims that Bartemius lives in my roof. :)