These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Nightmare Fuel: Marcworld, a fractal world consisting of an infinite number of Marcs of varying sizes, which has been going for at least 614 years.
Brought with an extra dose of Squick. Really, unless you have a strong stomach, it's best to just skip it.
The Woobie: 'Rumy must suffer' became a truism among the fans of Fans!; she also became one of the most sympathetic characters in the series because of it.
In the revival starting in 2008 with the "Magial Thinking" super-arc, definitely Hilda. She catches on to the nature of the big bads too early and for that, they kidnap her, replace her with a simulacrum, torture her for months, and force her to watch as her duplicate does a number of horrible things, all of which she can actually feel due to her being connected to the simulacrum. Even after the simulacrum was destroyed, her consciousness was floating around in a big black place, forced to watch the rest of the events of the comic, and both she and the readers were unsure of whether she's alive or dead, and not knowing is absolutely maddening (for both her and the readers). Even after she's been rescued and recovered, her experiences have so traumatised her that she is unable to engage in the pursuits that were once her chief joy in life (such as crosswords).