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

by Garth Nix

He fixed things with talk far more often than with force. But what people remembered and talked about was always the action.

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.

“But what afflicts Ellsworth is not some disease or condition that can be explained in our modern world. He has been possessed by an ancient evil, a creature of the deep darkness, long imprisoned, who was yesterday freed.”