"I have battled hundreds of these machines," said Eunicornus. "All automata in this facility are under the personal direction of Magos Passivity-SEA."

*

It is an awful thing to hear a robot scream. 

A hundred is so much worse.

The domain of the Datasmith is a nightmare on par with the worst excesses of the Ecclesiarchy. Massive wooden bonfires have been constructed and set alight, with the wretched iron skeletons of howling robots still writhing in their cores. Crucifixes have been constructed of reinforced iron and robots have been stapled in place with enormous piston-driven nails the size of a human arm. Here and there are raised altars where robots have been chained in kneeling positions, their armour stripped down to expose electrical circuit boards, screaming into their knees as they are whipped endlessly by the arc-scourges of Martian priests. When a priest tires they hand off their weapon to a colleague and withdraw, to eat, rest, pray and sleep - so they will be strong enough to continue the torture when their shift next begins. 

The [i]screaming[/i]. It's authentic, you'll give it that. That's really what it would sound like if you tied down a Tyranid termagaunt and electrocuted it continuously for weeks. The recording session for that sound file must have been - better not to think about it. But - the worst part is that the scream sound files are never more than a minute long. Every minute, at different intervals for different robots, the sound cuts off, there's a second of static, and then the scream continues again from the beginning. 

Do the machines feel pain? Or do they just know how to scream like they do?

Such are the secrets of the Omnissiah.

On a raised section of the catwalk, halfway between factory overseer's office and Inquisitorial throne, sits Passivity-SEA, resplendent in ceremonial robes of white and red. She is giving her personal attention to one particular combat automata, twin mechadendrite multi-meltas rising above her head boring minimum-intensity beams into the optical array of a hulking machine the size of a dreadnaught. The beams cease, and a servo skull swoops in close to wrench the semi-molten camera from its socket - and then turn it around so the tortured machine can behold the twisted wreckage of its own face.

Passivity-SEA looks down at it with pitiless human eyes, and then with the casual flick of a remote terminates its scream so that she can look to the two of you.

"Praise Him," said Passivity. "The Master of Machines, the Master of Mankind."