“Please undo what I’ve done, Lord,” she said. “I will never ask anything of you, ever again, if you just give me back the life of Gideon Nav.”
“I can’t,” he said. He had a bittersweet, scratchy voice, and it was infinitely gentle. “I would very much like to. But that soul’s inside you now. If I tried to pull it out, I’d take yours with it and destroy both in the process. What’s done is done is done. Now you have to live with it.”

Gideon the Ninth - Epilogue