Nightmare Fuel / Raising Steam

• The descriptions of people dying via steam. One second they're alive, and then there's just a pink mist… and bones.
  • A number of the 'delvers' - mooks for the bad guys - die by falling under a moving train, are set afire by the coal furnace, or encounter Lord Vetinari armed with a shovel. The book had already gone out of the way to establish that a lot of the grags' foot soldiers were just young, misguided traditionalists sent in as Cannon Fodder by the real villains.
• The grags attack a wedding and kill the bride because she's a dwarf who was marrying a human. They attacked a wedding and killed the bride. If not for one Dwarf attending - despite being a moderate conservative opposed to the mixed marriage - fully armed, it's almost certain the whole wedding party would have been massacred.
• The bandits near Quirm were eating goblin children, and nobody in Quirm knew about it.
  • And the local goblins did know, but never actually told anyone else, presumably still assuming the other races despised them too much to give a damn.
• The grags consulting a unnamed dwarven artificer from Ankh-Morpork on how to stop the Iron Girder from getting to its destination. The artificer tells them the best ways to do what they want and is allowed to leave by the grags' leader. He doesn't catch on to what the leader is actually saying, takes his payment while moving to get out of there. He gets his throat slit before he can even leave the cave he was in, just because he was from Ankh-Morpork and the grags don't give gold to unbelievers or people from the Big Wahoonie.
  Unnamed Leader: Well done, my friend. Please take this gold as a token of appreciation and, yes, we do know where to find you and every member of your family as well.
• The unnamed dwarf panicking about the "terrible sin" he'd committed (making friends with a troll) is unnerving in the extreme, especially as it feels a lot like someone panicking about a gay relationship.