Master adapters, not every shoggoth attacks to kill. Very rarely, a shoggoth incapacitates a victim, then enters its new host through the mouth, nose, and other orifices. Why the shoggoth does this is unknown. Perhaps it is to explore beyond its accustomed haunts with a degree of anonymity. Whatever the reason, the shoggoth enters the body, seeping into the interstices between the host’s own internal matter, down to the cellular level. Upon coming back to its senses, the host retains its general health, going about its normal business, often unaware that its body has become home to a new tenant. For its part, the shoggoth acclimates to its new environs, absorbing awareness of its host’s bodily and cognitive functions, studying everything the host sees, hears, senses, and does. With its impressive imitative abilities, the shoggoth can soon recreate with near perfection just about any sound that has been heard by the host body.
Over time, changes occur. The host’s appetite increases dramatically to sustain both itself and the shoggoth within. Food not normally consumed by the host body is fair game, as the shoggoth can absorb just about anything. Gradually the shoggoth asserts more and more control over the host’s mental faculties and movements as it becomes more assured in its new situation. Hosts experience strange appetites, odd humors, blackouts, and worse. They may become very unlike their old selves as the shoggoth pushes aside the host’s consciousness and commits shocking acts. Sometimes the host is aware of these transgressions; at other times they may be blissfully unaware of the horror lurking within and the ghastly things that it does while they are blacked out.
For all the horror of the invasion, the host body does enjoy some dubious perks: any bodily illnesses extant in the host form are typically targeted and eradicated by the shoggoth. Additionally, the host body experiences all the immunities possessed by the shoggoth: fire and electrical damage are greatly reduced, physical weapons do minimum harm, and so on. The shoggoth may lend its not inconsiderable physical might to the cells of the host body, boosting strength and endurance of the host form to near its own levels. Mimicking the sounds of anything or anyone heard is child’s play. The host’s skin may take on a slightly waxen appearance as the shoggoth’s plastic form insinuates itself at the microscopic level across the fibers and tissues of the host body.
Those who eventually become aware of the shoggoth within themselves typically despair and go insane with the knowledge. Twenty-first century medical imaging might detect the presence of the shoggoth lairing in a host body, but only advanced, non-human technology is capable of removing the shoggoth with any hope of the host’s survival. A rare few—truly evil, disturbed individuals—may enjoy the occupancy of the shoggoth, as it grants them abilities beyond mortal ken. On very rare occasions, the afflicted may match their match their mental strength or inner power against the will of the shoggoth; if the host mind is victorious, the shoggoth may temporarily be subdued to obey the host mind’s will. This is a tentative situation at best, as every new command requires a similar contest, as does controlling the shoggoth when it takes a mind to doing something of its own initiative.
However the host may feel about the shoggoth’s occupancy of their body, make no mistake: it is a parasitic invasion that ultimately spells doom for the host. The shoggoth may, at will, extrude some or all of itself from the host body to assault targets, typically through the mouth. If the shoggoth does this with some care for its host form, the host suffers no bodily harm. However, the shoggoth can just as easily at any time ‘explode’ from its host in a gory mist, leaving behind a hideous steaming pile of bloody slurry and shredded meat. It will often do this if threatened, or if it senses an opportunity to surprise a foe or future meal.
A shoggoth may take a human host or any other convenient animal it encounters and overpowers. It may spend years moving from host to host, leaving behind a bloody trail of broken lives and inexplicable mystery.