The top of the staircase ended at a seemingly unsupported pier of wood, a walkway no more than an inch thick and barely two feet across, with darkness on all sides. B stepped onto it, and Marla followed. There was a doorway at the end of the walkway, standing open, and white light beyond.
B hesitated on the threshold. “I…I don’t know where we are now, Marla, but if we step through this door, we’ll be even farther away from the world we know. We may be miles and miles away now, or whatever the spiritual equivalent of miles are, but once we go into this room, we’re light years away, you know?”
“Nothing ventured,” Marla said. “I’m not about to turn back. Are you?”
“I guess not. I just wanted you to know what we’re stepping into.” He went through the door, and Marla followed.
The room was hexagonal, or so Marla thought at first. She quickly revised her opinion to octagonal, then decagonal, and then she simply gave up, because the walls were changing, too subtly for her to notice the transition. The walls of this faceted room were mirrored one moment, then opaque crystal, then obsidian. The ceiling was so far overhead that it vanished into darkness, and the light seemed to come from the air itself, the brightest portion falling on an empty wooden chair in the center of the room. The chair was as simple as it could be, made of the same dark wood as the corridor walls, with a straight back and narrow arms.
“There’s no one here,” Marla said.
“There will be,” B said.
For an instant, something white flickered in the chair, a shape filling it, and then the chair was empty again. Marla heard a distant crackle, like static on a radio between stations.
Suddenly, in the kind of insightful flash that made her such a capable sorcerer, she understood. This wasn’t the Portable Witch, or the Biddable Witch, or the Pebbled Witch. It was—
“The Possible Witch,” B said. “That’s what she is. She deals in the possible.”
Marla nodded, impressed. He’d figured it out as quickly as she had.
Then the witch was there, dressed all in white, sitting in the chair. She—it, really, but for convenience, she—was immaterial at first, then gradually attained opacity and solidity.
“I’d expected three,” she said irritably. The possible witch was an old woman, dressed in a white gown like a choral robe, and she sat stiffly (there wasn’t really any other way to sit in such an uncomfortable chair, Marla supposed) with her fingers gripping the ends of the armrests hard, as if she were holding on to keep from flying away, which could be possible, for all Marla knew. Her face was pale, her hair mostly gray with streaks of black. Her eyes weren’t human, and they weren’t exactly insectile, though they were nearer the latter, faceted clusters of black glass with occasional flashes of pure crystal or mirrored silver. “Sometimes there are four of you, the fourth one a god, and on rare occasions there are five, the fifth a very old mortal man, but there are almost always three. Two of you narrows it down anyway, quite a lot, makes it easier, but it’s not what I’d expected, not what was most likely.”
“You know who we are, of course,” Marla said. “And I think we know what you are. The Possible Witch, yes?”
“I stand at the center of things,” she said. “Though I don’t just stand. I orbit, I oscillate, I vibrate. Every possible world passes through my sight. Some are more possible than others. Sometimes I’m dead. Mostly, these days, I’m dead. That’s why it took me so long to find you. There are so many possible worlds, and locking in on one in particular is hard, when I exist in so few of them now. But here I am. And it’s the two of you who’ve come, and it’s now, at this particular time, that you’ve come. Which means you’re not trying to undo damage, but prevent it.”
Marla nodded. “We need to stop Mutex. We need to know where he’ll be tomorrow, when I’ll be in a position to stop him.” Assuming Ch’ang Hao came through with the snake anyway. Ch’ang Hao was clearly the fourth one that the Possible Witch had mentioned, but she had no idea who the “very old mortal man” was. Probably a potential ally who’d died before Marla even met him.
“But you don’t want to know if you’ll stop him?” The witch’s inhuman eyes glittered.
“Of course I do, if you know that,” Marla said.
“Too close to call,” she said promptly. “I see just as many paths one way as the other. Everything branches, you know. Every decision, every option. The universe doesn’t make choices. It does everything, even very unlikely things, somewhere. There are some unlikely places in the universe. In this branch, in this world, it could go either way. You might win, you might lose. Doesn’t much matter, really. Lose here, win somewhere else. So why worry? That’s what I tell everyone who comes to see me, which is lots of people, when you take into account all the different worlds.”