The Waking Dead
This story is part of the community effort on the Emperor's Nightmare chapter.
The Waking Dead are truly mad. For the safety of their brothers they are kept powered down and armless. Watched over constantly by the Master of the Forge.
291.M40. There is a lone sleepless librarian dreadnought in a long, dark chamber among his kind. They are tended by many reverent techmarines and servitors. Their autosense eyes are dark but the charnel broken bodies inside their tombs are wide awake and restless, listening acutely to the muffled sounds of work going on outside the dark.
Suddenly and without warning the librarian strikes, invoking the machine spirit of his armour to jolt to life! The mighty war machine rises from one knee and crushes a nearby techmarine beneath his foot in a single fluid motion as he pulls to his iron body the weaponry and ammunition he has telepathically been holding for the last twenty-eight minutes and sixteen seconds. In moments the librarian has gunned down the entire room, telepathically tossing aside cover even as his remaining brothers flee behind it.
But he does not see his brothers. They are shape changers. Vile xenos beasts that only wear the shape of his brothers. He butchers the rest of them for the honour of the chapter and vanishes into the labrynthine service vents, attacking in guerrilla raids over the next month until he has crippled the battle barge. He knows if he lets the aliens proceed they will return the ship to his homeworld and bombard it with cyclonic torpedoes, obliterating all life.
In desparation, he bonds with the machine spirits of the engine core, destroying the gellar field even as he overloads the warp engines, banishing the nightmare creatures back to the hellish plane they came from.
He does not remember his own name but it matters not. Even in death he serves. He has saved the chapter. He has saved his home. He may finally rest eternally beside the Emperor with honour.