The whole world was thrown into chaos when the Great Fusion Wave hit.
According to experts, the inexplicable phenomenon had originated at a single point in the ocean off the coast of Japan, and had spread to the rest of the world within a single week.
Heralded by red skies and a wave of heat, the Fusion Wave caused no deaths, no destruction, but left the world irreparably changed. People, objects and even locations caught in the wave were broken down and permanently fused together in strange and unpredictable ways. Some cities reported that less than 1% of their population had been effected by the wave, but others boasted numbers as high as 50% or more.
Scientists even spoke of abstract concepts being fused or combined in ways previously thought impossible.
It was impossible to predict how two people might be combined. Some people were blended together neatly, becoming a single human being with a mix of traits of their two original selves. Most people were scrambled in a much more chaotic and uneven manner. Under the effects of the Fusion Wave, you might find yourself reduced to a second head mounted on someone else's shoulders, or even on their back or stomach. You might simply find your lower body replaced with that of someone else, or perhaps replaced with their upper body. There seemed to be countless variations of this scrambling, some as minor as an additional eye in an unusual place, and some so severe they resulted in bizarrely conjoined and rearranged life forms that barely resembled humans at all.
There were even rumors of people who got combined with objects, animals and even locations.
The effects on the fused humans' minds also varied greatly. Some found their minds and identities blended together, others maintained their individuality and gained joint control of their fused body. Sometimes, one identity was more dominant that the other, or exercised more control over the body. It was not unheard of for the two individual identities to eventually combine or reach an understanding, or for one to eventually totally override the other.
Society was of course greatly effected. Doomsday cults and conspiracy theories sprung up everywhere. New legal institutions were established to deal with complicated issues such as identification, custody and private property, which had become considerably more complicated in the wake of the Fusion Wave. Government-funded therapists and psychologists became an important part of life after the wave. Cosmetic surgeons also saw a massive surge in popularity, offering to help fused people achieve an appearance that makes them feel more comfortable in their new bodies.