How we cite our quotes: All quotations are from Harry Potter and the Goblet of Fire.
Quote #1
MR. WEASLEY: We've got to get out of here. Now! […] Get back to the Portkey, everybody, and stick together!
It doesn't take long for danger/the forces of eeeeeevil to make an appearance. The kids have been attending the Quidditch World Cup, and it's been fun…but now some followers of Voldemort called "Death Eaters" have decided to make an appearance. The non-Death Eater types find it pretty scary, so they flee.
Quote #2
HERMIONE: It's the Dark Mark, Harry. It's his mark.
HARRY: Voldemort? Those people tonight, in the masks, they're his too, aren't they? His followers?
MR. WEASLEY [nodding]: Death Eaters.
After the march of the Death Eaters, one rogue dude sends up something called the "Dark Mark" into the sky. Kind of like a firework, but evil and scary looking (it's a skull with a snake coming out of its mouth).
Quote #3
RON: Brilliant, isn't he? Completely demented, of course, and terrifying to be in the same room with, but he's really been there, you know? He's looked evil in the eye.
HERMIONE: There's a reason those curses are unforgivable. To perform them in a classroom. I mean, did you see Neville's face?
Ron and Hermione are debating the merits of a lesson they just got from Mad-Eye Moody. Moody is known for having caught/brought to justice tons of Death Eaters. So, he's with the good guys, right? Well, probably, but he showed off unforgiveable curses in class. That doesn't really seem like "good guy" behavior.