A possible future development of our real world where mirrors become the latest and most powerful technology. They have been extensively researched and are commonly used like an operation system in place of computers. All kinds of things are getting developed for mirrors, including video games, AR beauty filters and holograms, and many more. This is possible due to each mirror possessing a pocket dimension and being connected with other mirrors through unknown and possibly supernatural means. Most of it is common knowledge and is publicly available.

What isn't known to public, however, is that the memories of living beings such as humans or animals are able to imprint on mirrors and remain connected with them. This means that a mirror will remember a person who used it most frequently, and a trace of this person's soul will remain in the mirror indefinitely. It can't be confirmed whether this trace belongs to that person exactly and is their own soul, or if it's the mirror that copies the traits it has seen. The former suggests that there is a concept of a living soul, which can be physically trapped by mirrors and exist in their dimension. The latter would mean that mirrors possess or are able to develop a conscience of their own, and they use it to imitate other life forms. It may even mean that mirrors possess their own personalities and are capable of thought and choice.

This phenomenon is being researched by two separate organizations, both funded by the government of their respective countries. Any information about the first organization is highly classified, it has no media presence, hardly anyone knows of its existence, goals or even its name. Its main field of research are the reasons for souls being trapped in mirrors. Additionally, they research physical complications of mirror technology being integrated into common life and receiving prolonged use. Such complications include worsening eyesight, which can develop into partial or complete blindness, and various mental disorders, most commonly emotional instability of affected users. Their research involves testing on live subjects in controlled environment. Research results are processed carefully and none make it into the public.

The other organization uses these results in a different field, which has a lot less secrecy around it. Scientists have discovered a way to establish a connection between mirrors, which is only available to a being that is made of mirror itself. A normal mirror isn't capable of expressing itself through movement or language, even if it is possible for it to experience the world around in some way. Therefore, a being made of mirror needs to be adjusted and given a body capable of movement and language for it to be of use. This has led to creation of an android type called doppelgängers or dopplers, with a goal of traveling, observing and collecting any possible information for human researchers.

Doppelgängers or dopplers are only employed for science and are not made for personal use. They are advertised as "information gathering robots filling up a gigantic digital library" to the public, synonymous with knowledge and progress. The organization insists on the operations of dopplers being not dangerous to the public in any way, they only exist to serve science and have no capability of inflicting any sort of harm. Their information gathering is executed with great care and respect and is not used to be weaponized. Rather than being called spies for the government, they are publicly given the role of researchers. Just like marine biologists study marine organisms, doppelgängers study many different aspects of life which were previously unavailable to observe in detail. Their employment helps people understand the world and create a better future for everyone. The exact specifics of dopplers' work remains classified.

With the help of dopplers it was established that all the mirrors everywhere are connected with each other, not only around the world, but also throughout different points in time and even with different worlds and universes. Only dopplers are able to travel this way, and they are programmed to assist humans in their search for knowledge about the world. Every doppler is connected to the main info database and with other dopplers, meaning that they are operating as a hive mind. They are given certain tasks and assisted by researchers, which observe their movements and give direct instructions, while the doppler gathers information in a place they are assigned to. Hundreds of dopplers, each assembled by the human hand, create numerous entries in their knowledge database every day. This has allowed humanity to observe different points of time and fill information gaps about evolution, history, culture, biographies, fashion, personal conversations and many other things. The only requirement is that in this time there should exist a mirror in a specified or a nearby area. Otherwise the place remains unreachable and undiscovered.

Dopplers can easily blend in and attract no attention in any environment. This is possible due to every doppler having a shapeshifting ability. They can change their appearance into any living or inanimate organism they have seen. They are slightly limited by size of this organism, which is different to every doppler model, but otherwise they replicate any structures flawlessly. Doppler bodies are made of the tiniest mirror cells, each one of them can change its appearance, texture and even sound or smell. This is not a human modification, but instead an innate quality every mirror has, even the simplest one. A mirror exists to reflect any object it is shown, and while people were previously unable to confirm it, it doesn't only replicate the exterior of said object. Researchers have only recently uncovered this ability through accessing the dimension shown inside every mirror. It is said that mirrors see a lot more things that a human eye is able to, which is true. Mirrors replicate appearances together with molecular structures, that is, they are able to see and recreate individual cells of any object or being. That's why a doppler has no problem adjusting to its surroundings.

A distinct feature of every doppler is a presence of conscience, a mind or a soul. This is their most important feature that operates the entire body. Rather than having it be programmed mechanically, dopplers are programmed psychologically, in other words, they are educated and instructed of their role. A doppler has only one soul, which is the core of their existence and personality. To prevent a doppler having many different personality traits, memories and wishes, every component of their body undergoes special cleaning procedures and is returned to a blank state. Any possible presence of a soul is wiped away in this process, which makes this component fully controllable by the main personality core. Every component is replaceable aside from the personality core, damage to the latter usually can't be repaired, and without it the body can't function. If a part of their mirror body is damaged or lost, it is possible to create and put a new one in its place. Dopplers are taught how to purify mirrors to perform basic repairs and are able to mend their body without human help. Researchers can then execute a detailed extended maintenance once the doppler returns from their assignment.

Simply said, a doppler is made of one certain mirror that has gained a human conscience at some point, which was then put into a molded body made of blank lifeless mirrors. Their human soul pilots this mirror body like a mecha. It can change any body part and any cell at will, and it thinks and behaves like any human would. They have memories from the time they existed as a human, which could have been centuries ago. Researchers spend a long time educating dopplers about the real world and teaching them to cooperate. For better results, only mirrors with fitting personality qualities are chosen to be a core of a doppler. This means that souls sleeping inside mirrors are detected and analyzed before assembling them into a doppler, and they can then be rated for their suitability and possible performance. Approved personality traits mandatory for a doppelgänger are obedience, loyalty, curiosity, and honesty. They allow the person to be shaped into a tool for science more easily, and almost certainly guarantee that they won't rebel against their instructions. They also shape a person who can genuinely enjoy the job they are given and be interested in discovering the world. Every doppler is strictly (psychologically) programmed to be pacifistic, to the point that they won't use weapons or weapon-like objects for their self defense. They are taught to never inflict harm on a human and avoid harming other living organisms in general. It is highly effective and improves their public image.

A doppler is usually assembled by a team of engineers led by their main inventor, who is then assigned to them as their closest companion, either purely professional or as a family figure, a mentor or a friend. As they are a human researcher, they don't follow their doppler on assignments physically and can only give instructions and collect results. Inventors are usually very attached to their projects, because they spend a long time developing, refining and fixing them. They are usually the ones choosing the specifics of their future doppler model and a personality core fitting for it. Some actually treat dopplers like people, some think of them similar to their own children, some only see them as a research project, and so on. Due to their prolonged exposure to mirrors, engineers and lead inventors usually don't live a long and healthy life if they don't happen to choose a different profession eventually. All of them are under strict observation and are prohibited from disclosing too many details about their work.