Let me be upfront when I say that, as far as I know, there has only ever been one example of a character going Grimdark in Homestuck: Rose Lalonde. Jade’s brief time spent as Grimbark!Jade is not the same since her shift was caused by Her Imperious Condescension’s mind-control, not the Horrorterrors. The Horrorterrors are the key to becoming Grimdark, and as Rose displayed, they don’t control you; they invert your aspect.
Aspect inversion is a tricky subject. How the aspects invert is fairly simple - each aspect has an opposite, after all:
Breath - Blood
Light - Void
Time - Space
Life - Doom
Heart - Mind
Hope - Rage
But class inversion is harder to pin down. There is the Passive-Active dichotomy that Calliope discussed with Dirk (Prince is active while Bard is passive), but this is not an inversion. Inverting someone’s class would require finding the class that acts as its direct opposite. As such, I will be using @classpect-shet‘s Class Inversion Guide, which can be found here. The inversions of classes are as follows:
Heir - Mage
Seer - Witch
Knight - Rogue
Page - Thief
Maid - Bard
Sylph - Prince
For example, if I were to go Grimdark, I would go from being a Knight of Rage to a Rogue of Hope: one who distributes inspiration and positive emotions through inspiration and positive emotions. A Mage of Space would become an Heir of Time. Et cetera. When Rose went Grimdark and succumbed to the Horrorterrors, she became a Witch of Void: one who manipulates nothingness and ignorance through nothingness and ignorance. The meaning of her words were concealed to the point where no one could understand what she was trying to say. In other words, manipulating her secrets to make others ignorant. She managed to obfuscate the troll’s viewport of her and those who she was near, creating a Blackout. Vriska said as much when she tried contacting John after their encounter with Jack on the Battlefield when she advised him to get away from Rose so she could see him.
Unlike Trickster Mode - which is incredibly unlikely to occur even with a Cherub influence in their session - going Grimdark is a very real possibility for a session so long as players (probably Derse-dreamer) have a connection to the Horrorterrors. How one would turn it off is a matter of debate. Rose only returned to being a Seer of Light when she died, so there’s no way of knowing if it can even be stopped aside from death.
So yeah! Grimdark! I’m not sure how to end this, so I’ll just add a badass picture of Grimdark!Rose
“Servant of the Delphian Apollo Go to the Castallian Spring Wash in its silvery eddies, And return cleansed to the temple. Guard your lips from offence To those who ask for oracles. Let the God’s answer come Pure from all private fault”
F A N T A S Y . Z O D I A C virgo; the oracle// 23 aug - 22 sep
“The word oracle comes from the Latin verb ōrāre “to speak.” In classical antiquity, an oracle was a person or agency considered to provide wise counsel or prophetic predictions or precognition of the future.“
“Virgo’s are inquisitive and are very skilled at drawing information from people. This trait also makes them naturally intuitive. Combine this with their remarkable memories, and we see an advanced, analytical personality.”