Shared psychosis

Shared psychosis is presented as a condition in which two people share distorted beliefs and perceptions, and as a possible framework for understanding the partnership between Hannah Östlund and Jessica Friberg. In the investigation, it offers a way to consider how two women who were not relatives might have become implicated together in revenge killings, while leaving the source and distribution of their agency uncertain.

Definition in the Investigation

The novel describes shared psychosis, also called symbiotic psychosis, as two people sharing misconceptions, a persecution complex, hallucinations, and insanity. It notes that the condition occurs almost exclusively within families, and that one person is usually the more disturbed and dominant figure, while the other is governed by them. These are presented as general features of the concept under consideration, not as a settled clinical finding about either woman.

Hannah and Jessica

Jeanette considers the concept in relation to Hannah and Jessica after concluding that the two women murdered Fredrika Grünewald and Per-Ola Silfverberg. Although they were not related, they had grown up together, attended the same schools, and later lived near each other. Their long association makes the idea of shared beliefs relevant to the investigation, but does not establish that they experienced the condition or explain how their partnership worked.

The suspected killings appear within a pattern Jeanette connects to revenge. Yellow tulips had been left beside Fredrika, and Karl Lundström had received yellow tulips on the night he died. Jeanette also identifies yellow tulips and Sigtuna College as common factors in the cases. She wonders whether Hannah and Jessica might have killed Karl as well, but treats this as an open question rather than a proven fact. Shared psychosis frames a possible relationship between the women; the case’s connecting clues and the extent of their actions remain matters for investigation.

Unresolved Agency and Limits

The theory raises a question that its definition does not answer: which woman, if either, was the driving force? Jeanette considers the familiar model of a dominant partner and a more dependent one, then questions whether identifying such a figure would matter. Her immediate responsibility, as she understands it, is to collect facts rather than speculate about cause and effect. The concept therefore helps organize a hypothesis without resolving individual responsibility or providing a complete account of the crimes.

One of the women dies in a fire, and Jeanette thinks of Hannah and Jessica in a burning car as she reflects on how little will remain beyond the bodies and the evidence. In this aftermath, shared psychosis is not offered as a neat solution: it names a possible bond between the women while leaving the investigation to distinguish shared conviction, influence, and culpability.