Penitent Engines are mechanical engines piloted by heretics guilty of a terrible crime and want to atone for their sins. As usual they are the main walkers for the
Bolter Bitches Nuns with Guns. Thus they are given one of the worst imaginable punishments available to the Imperium. A multitude of wires and chemical injectors are implanted into the heretics spine, which are then attached to a mechanical suit of destruction. When not engaged in combat, their chemical implants inject feelings of guilt and pain directly into their brains, reminding them on how much they fucked up in life. Driven by their pilot's frantic need for forgiveness, Penitent Engines charge towards enemy forces heedless for danger, knowing that only in death can forgiveness be earned. Most pilots of the Penitent Engines are women since they mostly come from the Ecclesiarchy although male pilots are possible.
While somewhat Grimdark, it is kind of off set by the fact that the pilots of Penitent Engines are considered strangely hot and sexy by /tg/. Whether is due to the fact that the pilots are mostly female who are 'penetrated' and 'wrapped' around with so many wires like some kind of kinky bondage film or the fact that they are quite scantily clad in a single cloth robe is unknown, although most would point towards the former. Like the fucking baby carrier, the Penitent Engine suffers the general failure of exposing the driver to the elements. While it is to keep with the whole, "Dying gloriously in battle" shtick, they could at least put some cover so that the pilot could actually reach their enemies rather than getting sniped after immediately disembarking from a ship. Allegedly the chemical cocktail the drivers are drugged with gives them an insane endurance while letting them feel each wound so the fact their head's are likely to have gaping holes in it within a few seconds is actually intended. It helps that the people fielding Penitent Engines don't particularly like the people in them. Additionally the fluff states that pilots are left mostly exposed as a deliberate decision, to ensure that the penitent is protected solely by the Emperor's will rather than cowering behind ceramite plating.
See also Arco-flagellants, which are the same general concept.
Penitent Engines are typically armed with close-combat Dreadnought-class weapons such as a large, circulating power saws, Chainfists, or other Power Blades on each of the walker's arms, as well as Flamers or Heavy Flamers, which can be fired together or separately. The Penitent Engine can also use its legs to kick or stomp on enemy infantry since unlike the Dreadnought, the Penitent Engine doesn't have short, stubby legs.
|Forces of the Sisters of Battle|
|Command:|| Canoness - Ecclesiarchy Battle Conclave |
Ministorum Priest - Sororitas Command Squad
|Troops:|| Avenging Angel - Arco-flagellant - Battle Sister Squad |
Celestians - Crusaders - Death Cult Assassin
Dominion Squad - Retributor Squad - Seraphim Squad
Sister Hospitaler - Sisters Repentia
|Vehicles:||Exorcist - Immolator - Penitent Engine - Repressor - Rhino|
|Flyers:||Avenger Strike Fighter - Drop Pod|
|Saints:||Living Saint - Geminae Superia|