That's not why I remember this fic, but it does set the background for it.
Goodnight, Moon by Yahtzee (aka yahtzee63)
I can't even give you a summary. That would ruin it entirely. I love this fic beyond all reason. Well-written, well-constructed, and Joan's voice is perfect. Just click through and start reading...and you should probably bring Kleenex or a hanky.
God shuffled a little further down the aisle; the afternoon sunlight was shining through her gray hair, and it looked kind of like a halo. The books at that edge are NONFICTION/SCIENCE only if you don't define nonfiction or science too strictly -- all this stuff about past lives and aliens and hypnosis and stuff. But God looked completely serious when she pulled out a book about Dream Interpretation. "Though it wouldn't hurt to think about the Big Bang a bit. To ask yourself if beginnings are ever also endings."
"When you get all cryptic like that, I get worried."
She turned to me and pushed her glasses up her nose, very serious, just like a teacher. "Joan, during the next few days, you will have three dreams. Interpret those dreams, and accept what they tell you."