The Curse of Abhorrent Chirography

It begins with the written word.  A pamphlet, a scroll, a book– perhaps even a bit of graffiti.  This writing explains that society, and humanity itself, are irredeemably evil.  Those who read and comprehend the tainted script come to believe this themselves.

Once in the grip of the curse of abhorrent chirography, a person knows no peace.  Their thoughts and dreams are perpetually tormented by guilt for the original sin of being human.  It takes a terrible toll on their body.  They never experience a decent night's sleep.  Their wounds do not heal.

They project this torment onto their fellow men and women in the form of anger, hatred, even sadism.  They are compelled to express this hatred in writing– and they find that when they do so, their sleep is somewhat more restful, if not pleasant.  This of course spreads the curse further.  Yet still their wounds will not heal.  Even the slightest cut refuses to scab over, the smallest bruise remains purple for weeks.

The accursed become socially withdrawn, shunning the company of others and speaking rarely.  They prefer to communicate in writing, even when not actively attempting to spread the curse.  To the extent they do socialize, they mainly interact with each other.  The interactions are rarely pleasant.    

Eventually this becomes unbearable, and they take this torment out on others in the form of sudden, unprovoked violence– and find that when they do, they feel better.  Their body is finally able to heal itself.  For a time, at least.    

As the curse spreads, sufferers notice another effect: when they harm someone who suffers from the curse themselves, the benefit to the attacker is greater, yet the injury to the victim is longer-lasting and more debilitating, even compared to the suffering already inflicted upon the cursed.  Those who are cursed and wounded by one of the cursed become completely unable to sleep, or indeed feel any comfort or pleasure at all.  Even magical healing does almost nothing for them.  Only passing on the suffering by attacking someone can ease the pain.  

Like a plague, the curse may take a long time to take hold.  Yet it grows, and the rate at which it grows also grows, as the accursed not only spread the curse themselves, but drive each other to spread it more aggressively.  

Once the curse has grown large enough, there is almost no stopping it.  Those who have not yet become cursed can only run and hide, hoping to return and rebuild society after the accursed have wiped each other out.  Even then, the tainted writing is nearly impossible to completely eliminate; there are always scrolls and graffiti somewhere.  

Game Mechanics

Anyone who reads and comprehends at least a page of the writing that carries the curse (thoroughly– a mere glance is unpleasant, but not dangerous) must save vs magic, or make a wisdom save.  This save is modified by their intelligence modifier– a bonus makes it worse, while an intelligence penalty actually makes it easier to resist the curse.  On a failed save they are cursed.

Once cursed, a person needs 50% more sleep per night, and also constantly suffers from the effects of a single night of sleep deprivation regardless of how much they sleep.  They also heal far more slowly; a night's sleep does not heal injuries.  It takes a week of bed rest to gain the benefit of even one night's sleep.  

Writing several pages about how horrible humanity is will negate the need for extra sleep, and the sleep deprivation penalty, for a day.  Maybe longer if the writing is longer or more detailed.  This writing will of course spread the curse (other writing will not), and it does nothing to help the accursed heal faster.

Only violence will do that.  Wounding an intelligent humanoid will allow the accursed to both sleep and heal normally for one day for every point of damage inflicted– non-lethal damage counts just as well as lethal damage.  Not that violence stays non-lethal for long.

If the person so damaged is themselves a sufferer of the curse, they not only take damage, but become completely unable to sleep for one day per point of damage suffered.  This can be negated if they damage someone themselves.

All attacks by an accursed individual do receive +1 to hit and damage, and count as magical, against another who has the curse.  This does not apply if retaliating against someone who has attacked them within the past day.  In fights between the cursed, the first to strike has a massive advantage.  

The curse effectively traps its victims in an exponentially growing prisoner's dilemma, in which they are compelled to both spread the curse and attack each other first, lest they be attacked themselves.  It's only saving grace is that the curse tends to burn itself out– though not before taking much of society with it.