Yepper

¯\_(ツ)_/¯

Eridan didn’t go Grimdark, that’s a common misconception 

For the kids it’s the troll they interacted with the most prior to Act 6. John-Vriska, Dave-Terezi, Jade-Karkat, Rose-Kanaya

You can read the full theory here.  But in short, when a player is overly resistant to their role or if they are corrupted by an outside source then their role will inverse meaning that their aspect and class unofficially shift to their opposites. Light to Void, Space to Time, Witch to Seer*.

*This can change depending on how you classify the classes into Active/Passive partnerships

There’s an old theory that Eridan’s gills are deformed and don’t work as well as they should and that he wears his scarf to cover them. It would explain why he spends so much time above the water, even having his hive on the surface.

Right

Sollux, Mituna, Rufioh, Possibly the Serkets (we aren’t sure about the vision eightfold), and maybe Eridan if you subscribe to the theory that his gills are deformed

If she went grimdark then why could she speak perfect english?

Vriska