Genesis

Synaptids are those infected by Synapsum—a blight transmitted through living neural tissue of Synaptids. Synapsum takes the form of mutagenic neural cells that, when introduced to a host's nervous system, begin integrating with and rewriting the host's neural architecture. It is one of the more precisely targeted of Blight's blights, requiring direct contact with the nervous system to take hold; it cannot spread through the air, water, or casual physical contact.

The most common route of infection is through deliberate tendril connection—a Synaptid inserting their neural tendrils through an orifice (ear, nostril, eye socket, mouth) or directly into the spine or brainstem, and leaving behind living neural tissue in the process. The more forceful or sustained the connection, the greater the volume of tissue that may be left behind, and consequently the greater the risk of infection. Synaptids who connect carefully and intentionally can usually avoid transmitting the blight; the risk is highest in violent or poorly controlled connections, including some forms of predatory feeding.

Once Synapsum takes hold, the incubation period typically ranges from one week to three months, depending on the volume of neural tissue introduced, the host's biology, and the individual variation inherent to any blight. Incubation is rarely symptomatic in the early stages. The host may notice unusual clarity of thought, vivid dreams, or a growing sensitivity to the emotions and presence of those nearby—often attributing these to mundane causes.

As the blight matures, the changes become harder to dismiss. Their blood becomes dark and inky, noticeable if they become injured, and their skin becomes increasingly grayish, though still within the range of what might be possible for their original species—if a very ill one. They experience a pressure in the back of their head, though this is not painful. 

Eventually, the process will reach the breaking point, quite literally. Instinct will drive them to find somewhere safe—either secluded or among trusted individuals. They will feel and hear their skull crack, their now-inky blood pouring out the back of their head. They often collapse, twitching and writhing as the transformation fully takes hold—their fingers lengthen, their skin takes on cool tones, their eyes change, and tendrils burst out the back of their head. This will often leave them panting and exhausted, though they are flooded with endorphins and other biomolecules that leave them feeling quite satisfied. This entire process is painless, but intense. 

The mind is almost always fully intact following conversion. Synaptids retain all memories, personality, and sense of self from their prior life.

Hollowed Synaptids

In rare cases, a Synaptid who feeds messily—using tendrils to consume neural tissue while those same tendrils release their regenerative compound—may leave enough living tissue behind in the healing body to initiate a conversion without the original host-mind surviving intact. The Synapsum neural tissue integrates with the host body while it heals—not in the gradual, conversion-triggering way typical of infection, but rapidly, overtaking the host's neural architecture before the original mind can persist within it. The result is a conversion without a survivor: the body rises as a Synaptid, but the individual who previously inhabited it is gone.

These individuals are called hollowed—or hollowed Synaptids in more formal usage—named for the absence they carry. The soul that animates the hollowed body is, metaphysically, the same one that inhabited the original; it has not traveled to the ethereal plane and returned, but the neural substrate that held its memories has been overtaken. The hollowed wakes with no recollection of who they were, but with strong implicit knowledge—muscle memory, language, emotional resonances attached to places and faces they cannot name. They know how to move in their body. They reach instinctively for things without knowing why. The feeling of something missing is pervasive, and may remain so for a long time. Similar to anamnetics (see Soul Pathologies in Advanced Metaphysics), certain circumstances can allow them to "rewrite" old memories into their new mind. 

When a Synaptid community encounters a hollowed—and they recognize them immediately, through the same instinctive sense that recognizes all blighted—the most common response is one of gentle, deliberate welcome. The instinct runs deep: a mind that has lost all connection is one in acute need of new connection, and Synaptids feel the hollow in them as something close to grief. Communities offer tendril connection, shared memory, knowledge of what they are and what they can become. Some hollowed draw comfort from absorbing the community's history through connection; others prefer to build their identity forward rather than inherit someone else's backward. Both are respected.

The hollowed carry no blame for their origin. The Synaptid whose careless feeding produced them is a different matter, and how they are handled varies among different communities and societies.

Characteristics

Synaptids retain the general form of their original species, but with several distinctive changes that emerge during and after conversion. These can all be concealed through shapeshifting, though maintaining a disguise for multiple days at a time can be very uncomfortable.

• Grayish, cool-toned skin. This can range from light to dark, but must have a desaturated tint in the ranges of green, blue, and purple. 

• Bioluminescence. They are capable of bioluminescence in their tendrils, eyes, and other parts of their body, either at will or when they have high neural activity. This color is consistent, and shall be referred to as their "bioluminescence color." It should be a light (close to white) or bright (saturated) color with contrast from their tendrils. 

• Neural tendrils. Tendrils that are extensions of their neural tissue emerge from their head and spine, also forming their "hair." Their color is consistent, and shall be referred to as their "Synapsum color." It should be a very dark color, either black or of a similar hue as their skin. More details below.

• Eye variants. All Synaptids are capable of several different eye appearances, though some might find one type more comfortable or suitable: 

  • Dark: the entire eye is their Synapsum color. 

  • Iris: the sclera is their Synapsum color, and their iris is their bioluminescence color. 

  • Light: the entire eye is their bioluminescence color. 

  • Aster: the sclera is their Synapsum color, their iris is any color or not present, and they have a "pupil" that consists of branching lines extending from the center towards the edges of the iris, which can be their bioluminescence or Synapsum color. 

• Split mouth. At first glance, the Synaptid's mouth appears largely unchanged, though their teeth are sharp and somewhat beak-like, in that they have a larger central tooth on their upper jaw. However, the jaw and surrounding facial structure can split along hidden seams, opening wide to reveal additional teeth and internal structures. This typically only appears when feeding, not in daily expression or speech. 

• Long fingers and/or limbs — optional. Typically, their fingers are lengthened, but they may also have lengthened arms, legs, toes, etc. They may or may not have claws, which can be part of the hand, nails, or talons. If their fingers are normal length, it is common for them to have long claws. 

Synaptids live approximately 1.5 to 2.5 times the natural lifespan of their original species. A human Synaptid might expect to live 150 to 250 years. They do not age after conversion in the traditional sense, but will eventually decline. The aging process, when it comes, tends to be gradual—a slow dimming of psychic sensitivity, a lengthening of recovery time, a growing desire for stillness and inward contemplation.

Neural Tendrils

The back of their head and the line of their spine is exposed Synapsum tissue. Tendrils can form as extensions of this tissue, and each can be retracted fully or extended to any length. Tendrils can grow as thick as fingers or as fine as hair, depending on their intended use. Extended tendrils have a faint, pulsing luminescence when active, particularly during deep connection or intensive cognitive processing. Their "hair" is actually composed of incredibly fine tendrils. The area of exposed Synapsum may or may not include the area of their ears; many Synaptids do not have ear structures, only Synapsum where they once were. 

The neural tendrils of Synaptids act as limbs, sensory organs for all senses, and as a way to connect with others. Synaptids can adjust their sensitivity to different senses and softness of texture. They normally do not feel pain, and any injury to the tendrils is regenerated within seconds. 

The tendrils secrete a magical-biological compound that has a mild analgesic and strong regenerative effect, especially during connection. 

Diet

Synaptids require neural tissue to sustain themselves—specifically, a volume of fresh tissue roughly equivalent to the neural mass of their original species, consumed every one to two months. For humans, this translates to roughly the brain and upper spinal cord of one individual per feeding cycle. Oftentimes, they consume the whole creature to make use of the rest of the biomass to create abodes, cocoons, hiding places, etc. that they can feel and control psychically as if it were an extension of their own body. This is also "cleaner," but some simply consume the neural tissue and discard the rest. 

Cognitively complex neural tissue is nutritionally equivalent to simpler tissue in terms of raw sustenance, but it is significantly more rewarding to consume—richer in the compounds Synapsum processes for energy, and accompanied by the absorption of the consumed individual's memories and experiences. This is not a minor side effect. A Synaptid who consumes the neural tissue of another living being inherits everything that being knew and felt—every memory, every skill, every emotional echo of a lifetime. The experience of absorption is reported as intense and briefly overwhelming, like being briefly flooded with another life before the mind sorts and integrates the new material.

Hunger does not have to be satisfied through hunting. Synthesized neural tissue—biologically functional but cognitively inert—provides full nutritional sustenance, and is available in communities integrated with united society. It is widely described as "plain," satisfying in the way that nutritionally adequate food is satisfying without being particularly enjoyable. Many Synaptids in integrated communities use synthesized tissue as their primary sustenance and reserve fresh consumption for the end-of-life tradition described below.

Hunger can also be significantly reduced through connection. The proximity of other active minds—particularly through direct tendril contact—can partially substitute for nutritional intake, quieting cravings and extending the comfortable period between feedings. 

Somatic Form

Synaptids are able to shift into what is referred to as their "somatic form." In this state, their entire body shifts into Synapsum neural tissue, the same as their tendrils. Their forms are much more amorphous in this state, and they can more or less change their shape freely, though the "default" still resembles their original state. Their face tends to be smooth and featureless except for their eyes, though their split mouth is still there—simply hidden. They can have shifting bioluminscent markings and internal glows; commonly, their chest glows such that a ribcage pattern can be seen, though the pattern does not need to have the proper anatomy of a ribcage. 

If the Synaptid is an inheritor, it is common for them to consider the shape of their prior's somatic form as an alternate form that they are comfortable in, though the coloration will be their own. 

In their somatic form, all their senses are heightened and their psychic abilities are strengthened. However, they also have a much stronger desire to connect with others, and they are more vulnerable to electrical surges, which can potentially cause them to seize and lose consciousness, with lasting pain and disorientation even if they shift back, potentially lasting multiple days to a week, depending on the severity. 

Abilities

Neural Tendril Interface

The tendrils are the most versatile and defining feature of Synaptids. When extended and inserted into another individual's nervous system—via orifice, wound, or direct contact with exposed neural tissue—the Synaptid can:

• Read the connected individual's nervous system, perceiving their sensory experience, emotional state, and surface thoughts. With a stronger connection (involving more contact area of neural tissue), they can read memories and deeper thoughts. 

• Write to the nervous system. They can flood a system to produce pain, pleasure, calm, paralysis, or overwhelming sensory experience. With a strong connection, Synaptids can control others' bodies like a puppet. 

• Interface with electrical technology. Tendrils can connect to electronic systems through ports, wiring, or in some cases direct contact with powered components. This allows Synaptids to interact with technology in a manner comparable to biological computing, processing data, and in some cases directly operating systems with enough familiarity.

• Connect with other Synaptids. Direct tendril-to-tendril contact between two Synaptids creates a bond of a different quality than connection with a non-Synaptid—a full sharing of experience and thought, mutual and simultaneous. This connection is profoundly euphoric for both parties. When multiple Synaptids connect their tendrils in a group, this euphoria deepens and expands.

The compound released by the tendrils upon insertion has a mild analgesic and regenerative effect on the contacted tissue, healing any damage caused by insertion within seconds of withdrawal. This means connection, even through intrusive means, typically leaves no lasting physical mark on the host. The compound also has faint euphoric and dissociative properties, which means hosts who have been connected with often describe the experience as strange but not unpleasant—or even actively pleasant—regardless of whether they consented to the connection.

Psychic Abilities

All Synaptids have the following abilities that are passive or used as easily and instinctively as moving a limb:

• Psychic sensitivity. They can detect the emotional states and presence of others nearby without physical contact, though the precision and range of this sense varies between individuals and grows with practice. 

• Telepathy among themselves within a range of 100-200 meters, and with any conscious being within around 10 meters, range depending on the individual. 

• Levitation, which is commonly used instead of walking. 

• Minor telekinesis, allowing them to manipulate objects that are not exceedingly heavy. 

They can also have active psychic abilities, which differ from one Synaptid to another. These are abilities that can be used without physical contact or connection. Abilities that affect the autonomy of others can be resisted with enough willpower. Examples include: 

• Major telekinesis, allowing them to manipulate physical objects of much larger sizes.

• Mind control, ranging from planting suggestions to complete mental domination, where one is more or less a puppet to the Synaptid's will. Strong effects can typically only affect one or a small number at a time. 

• Transferring, restoring, altering, and erasing memories (though a strong soul may slowly revert the effects) 

• Projection, allowing them to move around as an invisible thought-being while their body is elsewhere

• Attention alteration, which can affect many at once and may include making others not perceive the Synaptid or another subject, or find something extremely attention-grabbing. 

• Mind reading, including thoughts, emotions, etc. 

Biological Supercomputing

Synapsum massively expands Synaptids' cognitive capacity, restructuring their neural tissue into something significantly more efficient and powerful than baseline biology. Synaptids process information faster, hold more in working memory, and perceive patterns at scales that would be overwhelming to an unmodified mind. This enhancement is not without cost: minds capable of so much more are also minds that can become lost in their own depths, and the compulsion to seek external connection—other minds to anchor against—is partly a function of this expanded capacity seeking something large enough to be interesting.

At high cognitive loads or during periods of deep introspection, many Synaptids enter states of deep inward focus, becoming temporarily vegetative in appearance while their mind works at extraordinary speed. Their tendrils may extend slightly and move with slow, exploratory gestures during these states, even while the rest of their body is still. These episodes are not dangerous, but they are notable, and can last from minutes to hours.

Regeneration

Synaptids possess strong regenerative abilities, accelerating healing of injuries substantially. Regeneration is supported by adequate nutrition; a well-fed Synaptid recovers from most wounds within hours to days. Severe injury—loss of limbs, significant organ damage—can be healed over the course of a week or two of adequate feeding. Injuries to the skull and tendrils heal particularly quickly, as the Synapsum is concentrated there.

Shapeshifting

Outside of their somatic form, Synaptids can shapeshift their appearance across a moderate range—enough to conceal all visible markers of their nature, including the solid eyes, the skull's altered structure, and any surface-level physical changes. They cannot wholesale change their body type or impersonate a specific individual convincingly, but a Synaptid who does not wish to be identified as one is unlikely to be caught in ordinary circumstances.