Reversers are anomalous creatures which appear to be capable of reversing time, residing within the Avana Galaxy.
Reversers are black roughly house-sized spheres. Their bodies are amorphous and can change shape, which they use to their advantage to see, by forming concavities on their surface to absorb light. Their innards are mostly devoted to their brain. Despite the size of their brain, they are likely no smarter than a rat.
Reversers photosynthesize, obtaining energy from absorbing light. Their black surface is to absorb as much light as possible. A reverser's behavior will change depending on the direction of time they choose. When going backward in time they will "unshoot" antimatter projectiles at celestial objects. From the perspective of the reverser, it is as if the celestial object spontaneously "unexplodes" and sends a projectile flying towards them, which they absorb. When going forward in time, they will absorb energy from a celestial object they had unexploded when going backwards in time by transforming into a thin spherical surface, enveloping the celestial object. When going forward in time, they will also collect energy from stars. It has been suggested that this is a method of reclaiming unusable within a reverser, since the energy spent reversing their arrow of time would outweigh any energy gained from this process.
To most observers, the switches in the direction of time of a reverser will appear as two reversers spontaneously forming, or two reversers colliding together and disappearing.
Reversers are "born" in pairs, with one born going into the past, and one born going into the future. A reverser is simultaneously the parent and child of the other reverser in the pair, in a manner reminiscent of the bootstrap paradox. This appears to be the only way reversers are created, though the presence of four observed births implies there is another method of doing so, albeit a method that appears to transcend causality. When a reverser dies, its body slowly disintegrates. To most observers, reversers which die while reversed will appear as antimatter spontaneously forming into a reverser, which is actually disintegration in reverse.
Reversers have been spotted for as long as interstellar travel has existed within the Avana Galaxy. Despite this, they are uncommon. It is unknown how many reversers exist, due to many of them possibly being the same reverser. There are at least eight reversers, as four reverser births have been witnesses. Serious research into reversers started after the observation of asteroids being destroyed with ludicrously high amounts of energy.
At first, reversers were considered evidence of time travel, however, it is likely that reversers influence the future in a manner that reverses entropy and leads back into itself to appear as if reversers do time travel. To test the hypothesis of reversers influencing the future, and to develop technologies which could bypass the laws of thermodynamics, memory modification technology for reversers was developed.
The first experiment involved implanting a false memory into reverser of having reversed and unreversed their arrow of time, in their past, and our future. This would, from our perspective, result in the creation of two identical reversers later. Shortly after, two as of yet unobserved reversers were reported, one of which later collided with the initial reverser and disappeared. Judging from the timeframe within the memories, it would've been likely that these two identical reversers would've been reported earlier, due to the thorough searching of space for reversers, suggesting that reversers are not time travelers. Later on, researchers observed that innumerous civilians within the surrounding area of space had been rendered braindead at precisely the same time the memory was implanted. After this, experimentation involving memory modification within reversers was outlawed, a controversial decision to this day.
Research into a possible connection between reversers and Aeterna Caligne is ongoing.