It is a well-known fact that a proper Dwarf is made up of these three essential elements: a beard, a heavy armour along with an axe or shield, and a foul temper. Indeed, Dwarves absolutely need to complain about something constantly, lest they wither away - so the wisdom of High Elves says anyway. The Grumblers personify that, albeit few call them that to their faces. These veteran warriors make up the backbone of many Dwarven armies, and their skill is only matched by their constant displeasure with this or that.
But one should not be fooled by this dour attitude. Like many of their kind, Grumblers will gladly put themselves in harm’s way for their allies and fight to their last breath if they have to. It would be difficult to find a more dedicated friend, even if securing the respect of grizzled Dwarven soldiers is no easy task.