People going mad from the revelation in fan works.
- Considering which settings Aeon Natum Engel uses, it's quite common. There is also a Running Gag with the readers going mad when they are figuring the Jigsaw Puzzle Plot.
- In the Slender Man fic By the Fire's Light, Jared Holloway spends the most time getting Mind Raped by the Slender Man. He briefly dances on the edge of going mad but decides to take his own life instead in the end.
- Children of an Elder God: Unsurprisingly, since this is a Cthulhu Mythos/Evangelion crossover, it happens a lot. Most of people who tried to pilot an Evangelion went mad, mutated or died because they had to synch with the mind of an Eldritch Abomination. Most of people who saw "The King Of Yellow" being performed went crazy and died when Hastur was summoned. And the list goes on...
- In the Star Wars fanfic series The Desert Storm, it's hinted on more than one occasion that Ben's extraordinary understanding of the Force comes from spending several years on the edge of insanity on Tatooine. He eventually manages to replicate the results with Obi-Wan, but without Obi-Wan going insane.
- Quinlan ends up falling to the Dark Side after he uses his Psychometry on Ben's old lightsaber and gets overwhelmed by Ben's memories from the future. This also causes Quinlan to experience a Loss of Identity since his memories get merged with the memories of his future self, Ben, Anakin, Ahsoka, Ventress, and Maul. Once they're sealed off, he manages much more easily, and eventually, they're erased on Dathomir, though he retains both a loose link to the Dark Side and a vague awareness of what he lost from some of the conversations he remembers.
- In Divided Rainbow, Celestia authorizes Discord to cast what amounts to a grand Masquerade-by-way-of-brainwashing on practically the entire world, to prevent this from happening to the Swapped Element Bearers. There are still several close shaves.
- In Equestria: A History Revealed, it is hinted that the science-loving King Sombra goes through this after a discovery pertaining to dark magic.
- The Transformers fic Eugenesis implies this is caused Wheelie's unique speech-patterns, just by looking at Quintessonian religious texts. Ratchet dismissed this as pure coincidence, but given what we learn at the end of the fic, perhaps not.
- It's later implied to be the reason for the Liege Maximo's Start of Darkness as well.
- The Harry Potter fanfic The Eyes revolves around Harry having grown up in the Miscatonic Asylum, and having long since been driven insane by what he has glimpsed of the true nature of reality. Once he's brought to Hogwarts, Dumbledore is driven mad as well after getting a glimpse of Harry's experiences and ends up comitting suicide. It's also revealed that both Ollivander and Professor Trelawney have also experienced the same thing long before, but in Ollivander's case, he's become so jaded to the point that he can function as a normal person, and Trelawney's powers of prophecy comes from her reading the Necronomicon as a child. Snape is driven unhinged by the events of the story, but Obliviates himself, allowing him to live out the remainder of his life in relative peace.
- The Infinite Loops: Most loopers tend not to react well when they find out they're in an infinite time loop, but some tend to...break harder than usual. There are two specific ways this can go:
- Sakura Syndrome, named after Sakura Haruno from Naruto. This occurs when a Looper's moral and ethical standards deteriorate thanks to the loop's ability to reset. They develop sociopathic tendencies, committing increasingly disturbing acts against non-loopers while excusing their actions because non-loopers "won't remember afterwards" and other similar excuses. Sakura was the first and by far worst-known case of this, and while she's mostly recovered thanks to channeling most of her impulses through her new occupation as a Mad Scientist, she has a tendency to relapse and has a well-known reputation throughout the looping community.
- Setsuna Syndrome, named after Setsuna Meioh from Sailor Moon. A looper suffering from this believes that baseline (canon) events are sacred and the key to "ending" the loops, and seek to maintain the baseline timeline at all costs. Unfortunately, this is not only pointless as the problem causing the loops is on a plane of existence above all loopers, but also impossible as baseline loops are not the only type of loops that a looper goes through, just the most common. There are crossover loops, Alternate Universe loops, etc. that all loopers will have one point or another, where maintaining a baseline timeline is an nonviable feat. The only way to set a looper suffering from this straight is to give them the introductory lecture (aka the "Welcome to the Multiverse" speech) multiple times and forcing them to accept that the problem is beyond their capability to solve.
- In the setting of the Mass Effect fanfic Inglorious Bosh'tets, this is what happened to many people who viewed the porno magazine Fornax's "Forbidden Issue," which featured Tali's idiot crewman Prazza performing a sanity-blastingly obscene sex act that thankfully remained undescribed.
- The Jackie Chan Adventures/W.I.T.C.H. crossover fanfic Kage has an example of this in the backstory. Long ago, a disciple of Kandrakar known forever afterwards as Althair the Mad Sage, read the scrolls containing the final prophecy of the first Oracle, N'ghala. Whatever he read horrified him so much that he burned those scrolls — and half of Kandrakar's library, in order to destroy any information on shadow magic — before leading his followers on a Great Purge across the universe, slaughtering thousands in order to try and prevent the coming of the "Incoming Darkness".
- One of the present sages believes that Althair went insane because he couldn't accept that anyone could topple Kandrakar.
- Twilight Sparkle of My Little Pony: Friendship Is Magic gets in on the act in The Monster Mash. They really need to erect a warning sign on that fourth wall.
- Maria Campbell of the Astral Clocktower: Played for Laughs. Maria comes from Bloodborne, where this sort of thing is common. Therefore she is convinced that any education will eventually lead to "cracking open skulls to look for eyes on the inside," and assumes the academy she attends is a ticking time bomb. Most people seem to assume that her comments about all scientists being mad are just off-color jokes.Maria: You have to be careful. Everyone knows talented geniuses are more likely to go insane and start doing immoral experiments on people than anyone else. First you start muttering to yourself, then you start wearing big hats and obsessing about dragons, and before you know it you've declared yourself pontiff and started trying to make yourself immortal.
- My Hero Academia: Unchained Predator: Ragdoll uses her Quirk to seek out the Slayer's location and finds out about his eternal war with Hell in Chapter 18. Suffice to say, her sanity broke in record time. In Chapter 28, Jeremiel, The Archangel of Dreams, has to do a memory cleaning on Ragdoll. While the nightmares wouldn't plague her anymore, she wouldn't remember the visions she saw, the carvings she made, or attempting to gouge Miruko's eye out with a scalpel in Chapter 26.
- The Night Unfurls: To defy this trope is one of the Good Hunter's primary concerns, which explains a lot of the decisions he makes in the story: why he appears as a human, why he uses his powers as a great one sparingly, and why he would go to great lengths to conceal any knowledge about Yharnam and the Eldritch Truth. It also happens to be a reason why the Hunter is reluctant to interfere with Eostia's affairs at the beginning of the original story, save for hunting down bands of greenskins and bandits. The trope is later invoked on Shamuhaza by releasing a bit of his eldritch might with a mere gaze. Seeing how Shamuhaza ended up, the Hunter has a very strong reason to fear the consequences from letting this trope happen.
- Pacific: World War II U.S. Navy Shipgirls. Those that survived their encounter with the first Abyssal ship eventually slipped into madness. Thanks to New Jersey however, this was soon prevented from happening again.
- In the Pony POV Series,
- Discord gets mad with a psychiatrist and exposes him directly to Entropy's realm. The results are not pretty.
- Viewing Havoc and Entropy in their true forms tends to drive mortals insane unless they're dead. Given they're the embodiment of Fear and the End of the Universe, that's understandable.
- Celestia refuses to explain the details of the Shadows Who Make, Watch, and Rule, the beings beyond the Elders, as their true nature would drive a pony insane. They're the writers, viewers, and Hasbro.
- Discord reveals to Diamond Tiara that her mother tried to kill her when she went insane (something Diamond quite understandably repressed) and that it was ultimately her stealing her mother's tiara caused it. This revelation drives Diamond insane and turns her into a Nightmare.
- Defied by Ash in Pokémon Reset Bloodlines. One of the reasons he never asked Delia any questions about his Disappeared Dad was because he feared the answers could amount to things he was better off not knowing.
- Played for Laughs in Project Voicebend, where Amon has the power to "mind-bend", giving minor characters awareness of their irrelevance. Bolin is also subjected to this and finds out his parents' deaths were nothing more than plot devices.
- In Robb Returns, finding out that the Old Gods not only exist but are powerful enough to curse him with blindness is enough to make Blackfoot crack.
- The typical fate of those who hear the voice of Dark Tails in Sonic X: Dark Chaos. Not only does it drive several individual characters like numerous Marmolins or Venus the Seedrian and Trinity to gibbering madness, it's mind-blasting enough to cause entire space fleets to go insane and destroy themselves.
- Thousand Shinji: When people saw Reigle — a ten-kilometer-tall, smiling Eldritch Abomination who looked like a human corpse that had been left in a hot swamp for a month — for first time, they went instantly and permanently insane.Standing up, [She] began to expand at a phenomenal rate, the same grotesque metamorphosis that had occurred before repeating itself on a scale a thousand times grander. Those that saw this happen invariably ran screaming when they did not collapse into quivering, vomiting piles of mental trauma. Those that had the misfortune for [her] ghostly flesh to pass through them were left gibbering wrecks, their sanity violently and permanently ripped from them by the horrific experience.
- This is described as having happened to the entire arakkoa race in Travels Through Azeroth and Outland.
- Played for Laughs in A Dash of Logic. In its rewrite of "Plankton's Regular", the mind-shattering revelation that the Krabby Patty formula never even existed causes Plankton's mind to literally shatter and he is hauled off to an insane asylum in a straitjacket, laughing and raving like a lunatic. Fortunately, it was just a virtual simulation by Karen.
- In Tobias Is Arrested, Yo
, two police offers go insane after they find out Tobias isn't a real person and was actually a fake identity made by six legendary Pokémon so they could compete in the Lily of the Valley Conference.
