The Bleeding Effect refers to a disorder wherein the genetic memories of one's ancestors begin to blend with the sufferer's own, real-time memories, often leading to difficulties in distinguishing between the two. In severe cases, this eventually resulted in mental breakdown.
The most common source of the condition tended to be overexposure to the Animus virtual machine, which deliberately sought to view an ancestor's genetic memories in a controlled fashion. The disorder was suggested, by Lucy Stillman, to be similar to "certain forms of multiple personality and delusional disorders."
- "Though the specific symptoms may vary from subject to subject, the end result is the same: they lose their minds."
- ―Lucy Stillman's e-mail.[src]
Subject 4, Daniel Cross, manifested the Bleeding Effect in the form of images of people and objects from the past, as well as unknown symbols. Additionally, he sporadically experienced the memories of his ancestor, Nikolai Orelov.
In around 1998, it was believed that the Bleeding Effect occurred naturally in Daniel, without prior exposure to an Animus. However, it was later discovered that he had in fact been placed in an older version of the Animus in around 1985.
By taking new medication and having weekly appointments with Dr. Sung, Daniel began to cope with the Bleeding Effect.
In her analysis of Subject 16, Clay Kaczmarek, Lucy Stillman e-mailed her overseer, Warren Vidic, to describe Clay's reaction to the Animus in detail. After having remained in the Animus for days at a time, Clay gradually became unable to control the Bleeding Effect, and was driven to insanity by the genetic memories he experienced outside the Animus.
Clay showed difficulty in remembering who he was and what year it was, going so far as seeming unable to recall his own name. However, he thought clearly enough to keep the goal of revealing the Truth in mind, and to leave the messages and clues necessary to do so. He became increasingly obsessed to this end, leading him to write warnings to future subjects in his own blood, around the laboratory he was held in, which resulted in his apparent suicide.
Subject 17, Desmond Miles, gained the combat and freerunning abilities of his ancestors, as well as the ability to use Eagle Vision, through prolonged exposure to the Animus. This was followed by several hallucinations of his ancestors' memories outside the Animus, however, Desmond was told that as long as the visions were shorter than thirty seconds, he was not in any danger. To begin with, the visions started out phantom-like and indistinct, but became longer and more vivid, at one point causing Desmond to black out.
Over time, Desmond's symptoms began to grow worse, and he despaired to Lucy Stillman that if he could not stop the slowly lengthening visions, it would not be much longer before he started "painting symbols on the walls," as Clay had.
Additionally, Desmond began confusing his ancestors' memories with his own; notably when he began to tell Lucy about "the last time [he had been] here" while they were exploring the tunnels beneath Monteriggioni, prompting Lucy to correct him that it had been Ezio Auditore da Firenze who had experienced the events.
Despite his concerns, the hallucinations proved quite useful, with Desmond being able to navigate through the tunnels under the Villa Auditore, and later the Colosseo and Santa Maria in Aracoeli, by following his visions of Ezio. Desmond even performed his first Leap of Faith at Monteriggioni by doing so.
However, Rebecca Crane also once e-mailed Lucy that Desmond had started screaming in his sleep since they had arrived at the Sanctuary. This concern was expressed in turn by Lucy to Warren Vidic, who was using the name of William Miles. Vidic responded saying he sympathized with Desmond's well-being, but reminded her that they needed him in order to locate the Apple of Eden.
Later, Desmond's condition worsened to the point where he fell into a coma, fragmenting his mind within the Animus. To revert the damage done to his psyche, Desmond finished the remaining memories from Altaïr Ibn-La'Ahad and Ezio Auditore to create a Synch Nexus, and ultimately regain his own consciousness.
- "Once you enter the machines and the transfer is complete, you will have the skills necessary to crush the remnants of Assassin Order, ending this war once and for all."
- ―Warren Vidic to several Abstergo agents.[src]
Similarly to the Assassins' attempts to train Desmond more quickly through use of the Bleeding Effect, Abstergo Industries also began to instruct potential Templars in a similar manner, in a large-scale project known as the Animi Training Program. Using multiple Animi, the trainees were exposed to the memories of previous Templars and non-Assassins, in order to incorporate their skills.
However, this was not the case in all their projects. For Project Legacy, which was open to a wider variety of candidates, messages of the DDS would constantly monitor whether their participants were beginning to show signs of the Bleeding Effect. In one such poll, the participants were requested to report if they were having difficulty recalling their name, or the present year.
- One of Lucy's emails in Assassin's Creed posited that some phenomena (such as past life regression) and mental illnesses (such as multiple personality disorder) could stem from a rare, naturally occurring Bleeding Effect.
- When Desmond relived the memories of Ezio's pilgrimage to Masyaf, and Altaïr's return from exile to Masyaf, ghostly images from Altaïr's past could be perceived. Whether this was a side effect of Eagle Sense's ability to track where targets have been, or merely the Bleeding Effect causing the memories to overlap, is unconfirmed.
- In Assassin's Creed: Revelations, Rebecca asked if the Bleeding Effect was part of Desmond's high concentration of First Civilization genes, to which William Miles replied that he believed so.
- The Lost Archive downloadable content for Revelations contained a mission titled "Bleeding Effect."