This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Left Behind
Left Behind: The Kids, in contrast to the adult series, is the fate of a group of young men and women as they struggle to cope with the horrid apocalypse. Their parents have all disappeared, everyone's getting beheaded right and left, everything's out to get them, and the adults that are left don't give a crap if the people they're threatening with death all range in age from thirteen to eighteen.
A thirteen-year-old dies in an earthquake in the beginning of the series. Gruesomely. Another teenager dies when her house collapses on her and traps her and her father in the rubble. The main group of teenagers are forced to spend the night in a cave full of snakes (despite the intense phobia of at least one of them), so they can avoid being caught and tortured by GC troops.
One boy gets drugged by his own dad in order to force him to take the Mark of the Beast. Two other teens get kidnapped, held for ransom, and threatened with death by drowning. The world they live in is basically anarchy + a police state, and no authority figures have time to help them.
Also, half the adult figures that the younger characters respect end up getting killed off (some very early on in the global earthquake ). The younger teens have to go through all the weirdness of puberty, with only slightly older teens to help them, while navigating a world of supernatural violence.
The book dealing with the earthquake has one of the main characters encounter a man with a bleeding man whose family died in the quake, leaving him the only survivor. He begs her to kill him, and then hurls himself into a flaming crater when she refuses. And the audio drama version makes this even worse due to the surprisingly good acting and terrifying music.
The Millennial Kingdom during Kingdom Come is actually pretty horrible when you think about it. Earth gets "perfected" so that the only landscape, ANYWHERE is either perfect rolling hills and flat plains great for agriculture, or calm seas, all of this under an endless blue sky with constant sunlight that is so bright, you have to wear sunglasses all the time. The only scenic geographical feature left is New Jerusalem, a giant city on top of an impossibly tall mountain that serves as the seat of an absolute theocracy where not adhering to the laws of the Bible will get you sent straight to Hell. Anyone who died and got saved comes back, but as a perfected version of themselves, incapable of any emotion other than happiness and love, as well as given absolute devotion to God. People who accept God by their 100th birthday become immortal, but their bodies still age at a slowed rate, meaning you have centuries-old people trapped in bodies that simply can't function properly anymore. And those that don't accept God by their 100th birthday? They go straight to Hell.
So to recap, Earth is boring and lost all natural beauty, everyone is expected to just farm or whatever, your deceased loved ones that got saved came back wrong, and not doing anything the theocracy wants you to, which is pretty much anything interesting, earns you an instant one-way ticket to the Lake of Fire.