Gideon’s toes found purchase and she stood, chest deep in water, goose-bumped all over from the cold. “What happened to praying that the tomb be shut forever and the rock never be rolled away?”
“My parents didn’t understand either, and that’s why they died,” said Harrowhark. “That’s why, when they knew I’d done it—that I’d rolled away the stone and that I’d gone through the monument and that I had seen the place where the body was buried—they thought I’d betrayed God. The Locked Tomb’s meant to house the one true enemy of the King Undying, Nav, something older than time, the cost of the Resurrection; the beast that he defeated once but can’t defeat twice. The abyss of the First. The death of the Lord. He left the grave with us for our safekeeping, and he trusted the ones who built the tomb a myriad ago to wall themselves up with the corpse and die there. But we didn’t. And that’s how the Ninth House was made.”
Gideon remembered Silas Octakiseron: The Eighth never forgot that the Ninth was never meant to be.
“Are you telling me that when you were ten years old—ten years old—you busted the lock on the tomb, broke into an ancient grave, and made your way past hideous old magic to look at a dead thing even though your parents told you it’d start the apocalypse?”
“Yes,” said Harrowhark.

Gideon the Ninth - Act Four, Chapter Thirty-One