The use of bionanotech to grow a control network inside a living being that allows the user to permanently modify or replace a subject's memory, beliefs, and personality.
Modo-level tech Rewrite Systems
Modosophont Rewrite systems are often divided into multiple categories and subsets of the technology, generally based on complexity and capability. The simplest, but most commonly used, systems are limited to such things as minor personality modifications (e.g., making a subject more patient, more confident, less aggressive, etc.) or mental adjustments (improving concentration, real-time control of emotions, etc.). Many DNIs, most exoselves, and virtually all personal nanomedical systems include such 'mind mod' tools as a matter of course and require little or no professional assistance or supervision when in use.
More complicated are systems that allow the implantation or removal of specific memories or skills without the use of an exoself. The level of cerebral bio-restructuring involved is significantly greater than that required for 'mere' personality modification, and most polities outside of the NoCoZo require some level of regulation and oversight of the technology to ensure that only trained professionals administer it and that it is used safely. While such memory adjustments (e.g., removing a traumatic memory of an accident, implanting a different interpretation of a memory that has resulted in a negative personality trait) are almost always voluntary, a few cultures may mandate the use of Rewrite technology as part of the criminal rehabilitation process.
The most complex Rewrite procedures involve the alteration, erasure, or replacement of an entire network of memories, personality traits, and reactions. Rewriting on this scale is rarely performed at the modosophont level and has been compared to the major surgical procedures of the ancient Information Age in terms of level of effort and potential dangers. Transapient oversight of the procedure is always preferred, if at all possible.
Transapientech Rewrite Systems
Transapient Rewrite systems are vastly more capable than their modosophont equivalents. Able to grow a full turingrade or superturing-level controller inside every subject using S1 or higher computronium, they can allow their user to restructure the minds and cultures of billions, trillions, or even quadrillions of sophonts simultaneously. If it wishes, a high level transapient can craft a new and individualized personality for each and every subject, erasing, modifying, or replacing every memory and trait with such skill that no discrepancies or conflicts are ever discovered, at least by lower-S systems (entities of an S-level equal to or greater than the 'author' of the changes claim to always be able to tell when Rewriting has taken place). When combined with transapientech restructuring of physical infrastructure and information systems, entire civilizations (whether modosophont or low transapient) can be remade and never realize that any change has taken place.
One of the most famous examples of large-scale Rewriting involves the former Infinite Light Crusade, a militant and ascetic hu supremacist theocracy that sprang up in the Hinterregions near the end of the Integration period. After colonizing and thoroughly developing their single star system, they began launching attack fleets toward nearby stars, conquering three neighboring cultures before running afoul of an unaffiliated and little known S3 mind known as Bluesong. Over the next century, the resulting retaliation, distributed via infectious spore technology and designed to hide itself from modosophont level detection methods, saw the entire Infinite Light civilization (some 250 billion near-baseline humans) remade into an equally dedicated, but utterly atheistic, culture of hedonics enthusiasts. Using their former war fleets to spread a message of better living through multi-species contact and recreation, the Rewritten Infinite Light Crusade would spend the next thousand years promoting multi-species cooperation, entertainment, and fornication across the Nexus and beyond before coming together to merge with Bluesong when e ascended to the Fourth Singularity in 5250AT.
While the example of the Infinite Light Crusade, or similar occurrences, is a cause of major apprehension in some quarters of Terragen civilization, the vast majority of sophonts are generally unconcerned about the issue, at least in the sephirotic empires. The long benign rule of the AI Gods makes it seem highly unlikely that they would suddenly resort to widespread use of such tactics to get their way. Of course, if they were to do so, or have done so in the past, no one would remember it anyway.
Hijack, Backup hijack - Text by Steve Bowers The crime of illegally copying an uploaded or stored personality, generally obtained during or after the backup procedure. These illegal copies can then be sold on the black market as virtual slaves, for use in computation or for entertainment.
Memetic Infector - Text by M. Alan Kazlev A sapient being used to infect societies or communities with a partiucular memeset. Memetic infectors resemble ordinary sophonts, but may differ psychologically, often having fanatical or one-sided enthusiasm for the meme-plex they are carrying. Infectors may be replicators (viruses) or non-replicators (memengers).
Memory Retrieval - Text by Anders Sandberg If one has a constant learning rate and a brain (or equivalent) of any given size then eventually the oldest memories are forgotten unless an effort is made to refresh them. If one decreases the learning rate then senility is a danger. As an alternative one can add extra memory - which in the long run means becoming posthuman (or postbiont, postvec, etc.) to manage all that information. Another alternative is to undergo periodic "childhoods" where the brain is made more plastic and one forgets a bit but not everything from previous incarnations, but this entails some loss of identity and some personality shift. Corporations like Psyber Retrievals, Inc - "Let us remember it for you!" - offer memory storage units for this reason.
Memory Storage, Long-Term - Text by Steve Bowers Memory storage for posthumans thousands of years old is often a problem. One popular (but clumsy) solution among some clades is to employ computronium implants, or even a small drone floating about for all the very-long-term memory storage. More elegant solutions involve a nanosome in each posthuman cell writing memory directly to redundant or specially set aside nuclear DNA.
Mindhacker - Text by John B Illegal profession in many if not most clades or polities. Specializes in extracting information from the mental processes of a target sophont. The best mindhackers can extract full information replicas without the target recognizing this, but that is exceedingly rare without a transapient intellectual rating. Mindworker profession.