"I don't suppose you've gotten any of the trash to behave interestingly."
"Not that I'd give any weight to. But then, I have no indication that I am a prophet."
"Giving a prophecy is considered a pretty clear sign. Beyond that, nothing especially consistent. But prophecies themselves are interesting. They have recipients, did you know that? As far as anyone can tell, each one is intended for a specific listener who is present at the time the prophecy is given."
"Only one recipient per prophecy has ever been clearly identified, but sometimes there are too many people present and not all of them follow up afterward. In the clear-cut cases, it seems the recipient always gets something useful out of the prophecy, although not always soon enough to do any good. And of course they all come true, but some of them are vague enough that that's not saying much."
"I had heard about the vagueness thing," says Bella. "I wonder why they're like that."
"There are competing theories. One of the better ones is that they are meant to be useful to the recipient at a specific moment, and too much clarity would lead to them going off early. But prophecy is not a voluntary exercise, so the seers aren't much help in figuring it out; they don't choose the wording. Some of them don't even remember it afterward."
Here is their room. Bella taps the doorknob to let them in.
"Good night," he says wryly, climbing up to bed.
She is back that evening.
Sherlock is a little slower waking up than usual, and his hair is a mess when he answers the door mid-yawn.
A voice barely recognizable as his, speaking as though from the other end of a vast empty room with exquisite acoustics and considerable echo, says: "The light of hope will erase the shadow of death."
"...What?" says Sherlock. "Is someone throwing Memory Charms again? I just lost another few seconds."
"I would never. You just said, um, 'The light of hope will erase the shadow of death".
"I just gave a prophecy," he says, blinking. "I was not expecting that. Write it down - exact words - you can't extract your memories yet and it might apply before you can."
Bella promptly writes down the exact words. "I have no idea what it means, though."
"Nor do I. But I am not supposed to. You're the one who is meant to understand it - not now, but at some future time when it will either be of some use to you or let Fate say 'I told you so' after the fact."
"That's not always a reliable indicator. But yes, it does."