Out of the Mirror, Darkness (Into Shadow, #7)

by Garth Nix

She looked around swiftly to ensure they were unobserved, darted forward, and placed a kiss on his lips before striding purposefully away. Harper raised his hand and touched his mouth, unable to prevent the awful thought that this momentary, fleeting kiss might be their last.

She spoke aloud, words Harper could not comprehend. They went in his ears and through his brain without lodging, and ever after he could not remember anything about them, not the sound or the meaning or the sense.

“I had such an awful dream,” she said slowly. “Have I been sleepwalking or something? You know, I haven’t been taking anything, Mr. Harper. Honest, I haven’t.”