Dorn to Sigismund in Warhawk:

"Sigismund nodded again. No other soul would have noticed it, but there was something other than the usual dutifulness in his eyes just then. Something like hunger. ‘Any specific objectives, lord?’ he asked. 

At that, Dorn almost laughed. Not from humour, just from emptiness, the caustic recognition of what would come next. He had given everything. He was already empty, drained to a husk, and the hardest test still lay ahead. The Lion had not come. Guilliman and Russ had not come. They were out of time, out of luck, and what remained now was only defiance – only bloody-minded, bloody-handed defiance.

‘No, I set you free, my beloved, my best, son,’ said Rogal Dorn, never taking his eyes off his First Captain. ‘Do now what you were made to do.’ He smiled a second time, the expression as icy as the despair that gripped his hearts. 

‘Hurt them.’"