Welcome to a tour of the most bizarre, 10 highly unusual, manifestations of folie à deux – the eerie phenomenon where two (or more) people adopt each other’s delusions. From historic married couples to modern‑day twins who turned a viral internet myth into a real‑life tragedy, this list dives deep into the dark side of shared psychosis while keeping the tone lively and engaging.
10 Highly Unusual Cases of Shared Psychosis
10 Margaret And Michael
In the 1800s, the earliest documented instance of shared psychosis involved a married pair known only as Margaret and Michael, both 34 years old at the time. Their joint delusion centered on an imagined group of unseen persecutors who were supposedly sneaking into their home, spreading dust and fluff, and somehow wearing down the couple’s shoes.
The pair were convinced that these invisible intruders were actively sabotaging their daily lives, leading them to obsess over every stray speck of dust and every scuffed shoe sole. Their belief grew so intense that it became a defining feature of their relationship, and they constantly discussed the imagined harassment.
While the true identities of Margaret and Michael remain a mystery, their case holds a special place in psychiatric history as the first recorded couple diagnosed with folie à deux, illustrating how shared delusions can arise even in seemingly ordinary marriages.
9 Folie A Trois: Three Sisters From South Carolina
In a twist on the classic duo, three biological sisters from South Carolina were found to suffer from folie à trois, a collective psychosis that later became a legal defense in each of their criminal trials. Their shared delusion painted a world where their mother—already battling mental illness—was poised to harm the children of one sister.
Before the breakdown, the sisters lived respectable, ordinary lives, but as adulthood progressed they grew increasingly enmeshed, spending virtually all of their time together. Their isolation intensified, and they began to believe that their mother’s influence was a direct threat to the next generation.
Religion became a central pillar of their shared belief system. The trio stopped sleeping, convinced that divine messages were being transmitted to them. When one sister’s husband tried to separate them, the women responded by donning pajamas, gathering the three children, and driving to a house they believed God had designated for their collective living.
Upon arriving, they forced their way inside, assaulting the residents and the police officers who intervened. Their violent takeover was a stark manifestation of their delusional conviction that they were fulfilling a divine mission.
After the incident, the sisters were charged with multiple offenses and placed together in a jail cell. There, they stripped off all clothing, refused to bathe, and performed bizarre religious rituals, attacking anyone who attempted to pass through the cell door.
The chaos required a force of fifteen officers over two hours to subdue and cuff the sisters. Notably, none of them had any prior criminal record before this episode. Today, they are prohibited from living near one another or visiting without strict supervision.
8 Folie A Deux With A Pet
Volume 149 of the American Journal of Psychiatry recounts a peculiar case involving an 83‑year‑old widow and her beloved dog, who together experienced folie à deux. The elderly woman became convinced that a noisy upstairs neighbor was purposefully moving furniture to irritate her, eventually escalating to the belief that the neighbor intended to force her out of her home.
Her paranoia deepened into a belief that the neighbor was attacking both her and her canine companion with mysterious “violet rays.” To protect her dog, she fashioned an “air‑raid shelter” beneath the kitchen table, instructing the animal to hide there whenever she heard any upstairs commotion.
Whether the dog truly shared the delusion or merely obeyed its owner’s commands remains a matter of debate. Nonetheless, the dog’s participation—hiding under the table at the woman’s behest—adds an unusual animal dimension to the shared psychosis narrative.
7 Folie A Deux, Religion, Demons, And Murder
Mr. and Mrs. A were two lonely young adults who met through a personal advertisement, quickly fell in love, and married after just a week of acquaintance. Their relationship seemed like a perfect match: she claimed to converse with the sea and night sky, while he had been diagnosed with paranoid schizophrenia since the age of eight.
Both partners embraced a shared belief that a “demon” speaking through Mr. A was actually the childhood “god of the sea,” which also communicated with Mrs. A. This supernatural partnership guided many of their decisions, creating a bizarre blend of romance and psychosis.
For several years, the couple roamed in search of work, following the demons’ whispered instructions. One night, a demon warned Mr. A that he would soon be killed and that Mrs. A would be raped. Acting on this premonition, the pair purchased a firearm.
During a dinner at a restaurant, the duo perceived two male diners laughing at them, interpreting the laughter as a direct threat. They fled to their apartment, but the demons urged them to return and exact vengeance. The couple obeyed, storming back into the restaurant and shooting the two unsuspecting men dead.
Following the murder, the marriage dissolved, and the couple went their separate ways, illustrating how shared delusions can culminate in deadly outcomes.
6 Nathan Leopold And Richard Loeb
In 1924, the United States was shaken by the chilling case of Nathan Leopold and Richard Loeb, two teenage prodigies whose relationship epitomized folie imposee—a form of shared psychosis where a dominant partner imposes his delusions on a submissive one.
Leopold, an intellectual genius with an IQ surpassing Einstein’s, viewed himself as superior to ordinary society and believed that his brilliance exempted him from moral constraints. He cultivated a disdainful worldview that placed him above the law.
Loeb, equally brilliant and the youngest graduate of the University of Michigan at the time, was the dominant figure in the pair’s relationship. Their secret romantic bond, taboo in an era when homosexuality faced severe stigma, intensified their mutual obsession with crime and murder.
Both men became fixated on detective fiction and true‑crime stories, turning their intellectual curiosity into a twisted game. They embarked on a spree of arson, burglary, and other illicit activities, each crime culminating in a perverse reward: sexual intimacy between the two.
The climax of their criminal partnership arrived when they lured 14‑year‑old Bobby Franks into their rented automobile, subsequently bludgeoning and suffocating him. They staged a fake kidnapping, attempting to mask their heinous act, but the “perfect crime” unraveled quickly, leading to a sensational trial.
During the courtroom drama, Leopold and Loeb maintained a flamboyant, almost celebratory demeanor, turning the trial into a media spectacle. Loeb later died in prison, and at the moment of his death, he was held in the arms of his lifelong partner, Leopold, underscoring the tragic depth of their shared psychosis.
5 Christine And Lea Papin
Christine and Lea Papin were French sisters employed as housemaids for the Lancelin family—Rene, his wife Leonie, and their adult daughter Genevieve. Their early lives were marred by trauma: their father had raped their older sister, and all three girls were placed in foster homes, later shuffled through orphanages and convents.
Living together in the Lancelins’ household, the sisters shared a cramped bedroom and endured social isolation. Christine, at 27, and Lea, at 21, were known for their quiet, obedient demeanor, rarely voicing complaints.
Their world shattered during a heated argument with Leonie Lancelin. In a sudden, violent transformation, Christine lunged at Genevieve, gouging out the young woman’s eyes with her bare hands. Lea joined the frenzy, attacking Madame Lancelin with equal ferocity.
When Rene Lancelin returned home with his son‑in‑law, he discovered the gruesome scene: the bodies of his wife and daughter strewn across the floor. Shockingly, the Papin sisters were found locked in their bedroom, some accounts describing them naked, lying together on the bed.
The sisters confessed to the murders and were taken into custody. Subsequent psychiatric evaluations focused on the intensity of their bond, suggesting that Lea’s personality had effectively merged with Christine’s, erasing any distinct identity.
Following their separation for treatment, Christine exhibited extreme distress, highlighting the depth of their enmeshment. While some historians speculated about a sexual relationship between the sisters, no conclusive medical evidence ever confirmed such a claim, and the sisters themselves denied it.
Their defense attorney argued that the sisters’ personalities had become so intertwined that the subordinate sister, Lea, ceased to exist as an independent entity, resulting in a shared paranoid delusion—a textbook case of folie à deux.
4 Pauline Parker And Juliet Hulme
In the mid‑1950s, two 15‑year‑old schoolgirls from Christchurch, New Zealand—Pauline Parker and Juliet Hulme—developed an intensely close, almost obsessive friendship. Their shared fantasies revolved around becoming Hollywood actresses and celebrated novelists, fueling a powerful codependent bond.
Their parents grew increasingly uneasy about the duo’s closeness, especially after a psychiatrist suggested that Pauline might be engaged in a sexual relationship with Juliet—a claim later denied by Juliet. The tension escalated when Juliet’s parents’ marriage disintegrated, prompting plans to send Juliet to live with her father abroad.
Both girls fiercely resisted separation, pleading that Pauline accompany Juliet. Their pleas fell on deaf ears, and the girls were left to confront an impending split.
In a tragic climax, Pauline’s mother, Honora, took the two girls on an outing. During the excursion, the girls brutally murdered Honora, an act that shocked the nation.
The defense’s insanity plea failed, and the girls were sentenced to prison. After serving a few years, they adopted new identities: Juliet became the acclaimed crime novelist Anne Perry, while Pauline resurfaced as equestrian teacher Hilary Nathan, both relocating to the United Kingdom but living separately.
The 1994 film “Heavenly Creatures,” directed by Peter Weir, dramatizes their relationship and the murder. Anne Perry later dismissed the movie as fictionalized, even suggesting that she participated in the killing to prevent Pauline from taking her own life if they were separated.
3 Morgan Geyser And Anissa Weier
Even younger than the Parker‑Hulme duo, Morgan Geyser (12) and Anissa Weier (also 12) formed a chilling partnership rooted in a shared psychosis. Both girls suffered from schizophrenia and psychotic spectrum disorders, which, combined with an obsessive fascination with the internet‑born myth of Slender Man, led them to a deadly plan.
Geyser’s best friend, Weier, was also a close companion of their victim, classmate Payton Leutner. The trio often spent time together, with the girls’ friendship deepening during a sleepover at Geyser’s birthday party.
Fuelled by the belief that Slender Man would reward them for a sacrificial act, the girls lured Leutner to a nearby park, where Geyser restrained her while Weier stabbed her multiple times. The girls then dragged the wounded girl into a forest, intending to leave her for dead.
Police intercepted the girls en route to the Nicolet National Forest, where they believed a Slender Man “house” awaited them. Unaware that Leutner had survived, the authorities rescued the victim, who managed to crawl to safety despite severe injuries.
Slender Man, a tall, faceless figure in a black suit, had become an internet legend, prompting a wave of copycat crimes. Geyser and Weier believed that the murder would grant them entry into his mythic mansion.
Both girls were found not guilty by reason of mental disease or defect. Geyser received a 40‑year commitment to a mental institution, while Weier was sentenced to 25 years, underscoring how shared delusion can propel adolescents toward extreme violence.
2 Folie A Famille: The Tromp Family
One of the most perplexing modern cases of shared psychosis involves the Tromp family of Silvan, Victoria, Australia. In 2016, the family—parents Mark and Jacoba and their adult children Riana, Ella, and Mitchell—abruptly abandoned their berry farm and embarked on a bewildering, spontaneous road trip.
Mark Tromp, the patriarch, was experiencing a mental breakdown, convinced that external forces were plotting to harm his family. His children, deeply enmeshed with him, adopted his delusions, believing that immediate escape was essential for survival.
The family fled without phones, wallets, or passports, leaving their home unlocked and their farm vehicles idling with keys in the ignitions. Their departure was a stark departure from their reputation as respected community members.
During the chaotic journey toward New South Wales, the siblings began to fragment. On the second day, the group split: Mitchell abandoned the car in Bathurst, later traveling by train to Sydney and eventually back to Melbourne. Meanwhile, Riana and Ella diverged, heading toward Goulburn, where they became separated.
Riana was discovered catatonic, hidden in the back of a pickup truck, and received immediate medical attention. Ella managed to steal a car and drive home. A few days later, Jacoba was found wandering the small town of Yass, subsequently hospitalized for evaluation.
Mark Tromp was eventually located near Wangaratta, still convinced that unseen enemies pursued him. The entire family was eventually reunited, and the parents, along with their children, returned to their farm.
Following the incident, the Tromps received comprehensive mental‑health care and have since resumed their lives on the berry farm. Remarkably, no physical injuries were reported, highlighting how a shared delusional belief can spark a massive, yet non‑violent, exodus.
1 Ursula And Sabina Eriksson
Swedish twins Ursula and Sabina Eriksson captured worldwide attention in 2008 after a series of bizarre, self‑destructive actions that epitomized folie à deux. At the time, Ursula resided in the United States while Sabina lived in Ireland with her husband and two children.
The twins reunited when Ursula traveled to visit Sabina. Their reunion quickly turned chaotic: they boarded a bus to London, only to be ejected for erratic behavior and refusal to have their luggage inspected. Authorities suspected them of carrying bombs, but no explosives were found.
After being dumped at a service station, the sisters proceeded to walk onto the middle of the M6 motorway. Unbeknownst to them, a crew from the TV series “Motorway Cops” was filming nearby and spotted the twins dodging traffic.
Police approached the women, at which point Ursula suddenly sprinted into oncoming traffic and was struck by a truck, sustaining severe leg injuries. While medics attended to her, Sabina also ran onto the motorway, where a small car ran her over.
Both twins displayed extreme agitation: Ursula told officers they weren’t real police and assaulted them, while Sabina, after regaining consciousness, attacked another officer and shouted about organ theft before being wrestled into an ambulance by six bystanders.
Investigators discovered the twins carried multiple cell phones, and Sabina’s husband was unaware of her whereabouts. After being released from police custody, Sabina was taken in by Glenn Hollinshead, a man she had just met.
While staying at Hollinshead’s home, Sabina’s erratic behavior persisted. She engaged in unsettling conversations about poisoned cigarettes before, in the early morning, stabbing Hollinshead to death.
Following the murder, Sabina fled, brutally beating herself on the head with a hammer. When a driver attempted to intervene, she struck him with a roof tile she had in her pocket. She then leapt from a bridge, landing on the A50 highway 12 metres below, shattering multiple bones.
The severe injuries slowed her enough for authorities to apprehend her. She received a five‑year prison sentence for murder, but was released in 2011 and returned to Ireland. Ursula, meanwhile, remained in the United States, recovering from her injuries.
Alone, the twins appeared ordinary, yet together they spiraled into a violent, self‑destructive partnership that illustrates the terrifying power of shared psychosis.