Left Hand

Left Hands are a recently discovered, and highly dangerous species of parasite recently discovered in the Universe of Design. Almost nothing is known about the discovery of the parasites itself, but over the course of the series a lot about their biology has been revealed.

General Symbiosis
The parasites will exclusively target human females for infestation and remain dormant until they reach about halfway through their adolescent years. At this point the parasite becomes active, changing the host's brain into a telekinetic organ. This can cause murderous rampages for a short period ranging from a few hours to several days, due to the brain's deterioration twisting the personality it holds. The parasite takes over the host through the spinal cord once the process is complete, giving them full control over the host body. This process renders the host clinically dead for all of a few seconds before immediately reviving them. At this point the Parasite becomes the active consciousness controlling the body, but because it has been connected to the brain, it has adopted all of the memories and traits of its host. In addition it goes to great length to keep the host body at least mostly functional and alive, resulting in little difference on a fundamental level. That being said the host loses all reproductive capabilities and any attributes of the original body not pertaining to immediate survival are allowed to atrophy.

Matter Distortion
The main danger of the parasites is that they are instinctively violent and destructive. In addition they posses the incredible ability to influence and distort matter outside of their bodies. This is most easily described as telekinesis, though various characters also say that such a comparison doesn't truly do the concept proper justice. Somehow they are able to enact force upon particles, pushing them in a certain direction, and subsequently causing physical objects to move. It is an ability shared across all of the parasites, but it is stated to reach its full efficiency only when a human host is present. Furthermore, both the scale on which it can be enacted and the degree of control that can be exercised over it various by case.

Specific abilities
A Left Hand parasite with a proper host is only limited by its ability to consider new applications for its abilities. Weaker levels of matter distortion can be used to tear about and heal bodies with similar degrees of efficiency. A wounded Left hand left to its own devices will reassemble broken or damaged body parts one molecule at a time, and when in combat it is common to see a man torn apart from the inside out by distortions. As control improves more applications become plausible, such as making a broken or deformed body simulate walking by pushing individual limbs in various directions, breaking down and reconstructing various body parts to form improvised weapons and organs, or even causing air particles to vibrate to the point of spontaneous combustion.

Weaknesses, Flaws, and Complications
The Left Hand parasites are only capable of symbiosis with female hosts. This is because of a minute difference in the male and female immune systems. Where the female immune system can be tricked into viewing the parasite as another organ, the male immune system will always reject it and attempt to kill the parasite, causing the death of the host as a result. Because of this the parasites have evolved to lay eggs within male humans who will then carry them with them until dying when the young mature, preferably in a populated area with plenty of potential female hosts.

During the period of time in which the parasite is nearing full awakening, they modify the host's brain, changing it into a telekinetic organ rather than any of it's previous purposes. However, during this changing process, the parasite has not yet taken control, so the brain is in control while losing parts of itself to another functionality. This results in a warped outlook and personality, which is still in control of the host body and has access to the (somewhat limited) telekinetic abilities the brain is gaining. This often causes them to go on wild rampages, often committing mass murders and leaving a bloody mess of gore in their wake. This is when they are normally discovered by the organization. Once the parasite awakens, it has full control of the body and the brain, stopping the rampage (unless the host's original mindset would have done the same). If the parasite comes under significant threat and is disabled somehow, it may allow this warped version of the host's personality to take over for some time, until the parasite has recovered enough to control it again (This is a last resort option, as it is very unpredictable given the mind's state).

The parasites have almost no consciousness of their own, acting almost exclusively off of impulses and instincts compelling them to infect and reproduce. As a result, when they connect to the brain of a host, they take on the same memories and traits. There is little difference in personality and behavior regarding a host before and after the parasites awakening (excluding the period before the first awakening).

Left Hands need to have an understanding of whatever matter they attempt to distort. They can tear an ordinary human apart by pulling separate bones in different directions, but only because they already know the bones are there to begin with. If they cannot see something, they can only pull or push what they assume is there in a given direction. For example if there were some sort of hip or knee replacement they did not know about, they could still move it along with the bone, but they would have to concentrate on the object to move it specifically. Taking advantage of this quirk, those who would contain a Left Hand would often carry weapons or even clothes made of a currently unknown black material, which the parasite is unable to focus on.

Matter distortion generally does not work on other Left Hands. As a result of something called the Empathetic Feedback Response, Two Left Hands who attempt to form distortions on another's bodies will subconsciously synchronize to each other's vibration frequency and stop out of instinctual confusion.

Role
In the context of Design, the Left Hands' existence is a closely guarded secret, known only to few branches of the military, and the Refinoc foundation, both of whom held a mutual interest in weaponizing them. The military hoped to have a unique and deadly bioweapon to use in case of emergencies. Refinoc, led by a man only referred to as the Director, originally wished to control them and drive the species to extinction for the sake of humanity's safety. This is an intention that would be lost with the Director's death. The idea of weaponizing them was continued to keep government funding flowing however.

Trivia

 * The parasites were named Left Hand by the original Director in reference to medieval warriors claiming that left handed fighters were more difficult to face on the battlefield. In his mind it only made sense to name humanity's natural enemy after such an adaptation.
 * After the original Director's death, Cleo Dahmer chose to rename the Left Hands God Bearers, as where her predecessor held a deep fear and hatred for them, she openly admires the species.
 * The Empathetic Feedback Response, which prevents Left Hands from using matter distortion on one another directly can be circumvented with the use of various drugs and poisons to reduce feelings of empathy or even ignored entirely if a host happens to be a sociopath.