A Character Concept - Third Shift
Third Shift is a mass of organic and inorganic matter that has the appearance of vine-like tendrils coated in thick, black sludge. It will commonly infest convenience stores and other 24-hour locations. It manifests only after the last employee leaves the store for the day, and will man the register as well as any other station necessitating human interaction by creating a vaguely humanoid-shaped mass - along with red glowing eyes - in those locations, remaining there until an employee reenters the store in the morning; when this happens, Third Shift will seem to "seep" into any perceivable crack or gap, including the space between floor tiles, corners, behind shelving units, and so on. It will, over the course of the night, spread over the entirety of the store, seemingly cleaning the dirt and grime off any surface, as well as restocking and facing merchandise according to the given store's wares.
Third shift is telepathic, but communicates via a strange psychic link that causes their words to take on the voice of the individual's thought pattern. Simply put, it speaks to an individual using their own thoughts. This allows Third Shift to easily anticipate and transport the merchandise an individual wishes to purchase to the point of sale without any effort from the costumer. Ther merchandise will have no trace of sludge or any dirt or impurities at all, and will often also be bagged.
Third shift accepts most methods of payment, including checks, card, and "tap" payment, even if the infested store is not equipped with the technology to do so. In such cases, Third Shift will automatically convert these methods of payment to an acceptable form for the infested store. For example: if a store only accepts cash, and a customer uses a credit card, Third shift will apparently spawn cash units from its shadowy form to fill the register.
In the event of an armed robbery or similar event, Thrid Shift will detain the perpetrator(s) with the same tendrils that cover the store; at the same time it will notify local authorities and wait patiently - continuing to serve customers and carry out its other "duties" - until they arrive.
Additionally, every instance of Third Shift seems to be connected to the same psychic "hive mind," as it will remember customers across multiple stores, even if the given customer has never enetered that store before. However, every instance of Thrid Shift is also unique, having different personalities for every individual humanoid manifestation.