It had no true thoughts, but functioned on basic instincts coded into it's DNA. Free of confinement, it sought a host.
Three tendrils the size of pencils pulled it's walnut like body up the wall. Its wet boneless mass squeezed into the air duct. The extensive damage done to the counterpressure system allowed it to bypass numerous containment systems.
Time had no meaning to the creature, it relentlessly squirmed through the system. Eventually reaching the HVAC unit itself, it sensed moisture and entered the condensation collector, which led to the sewer line.
It crossed half of town wriggling through the sewer pipes. The creature picked up a promising trail, detecting chemical compounds that were associated with a viable host. Upwards through narrower pipes, it followed its instincts.
Sophie was sprawled out on her apartment bathroom floor. She had severely overdone it celebrating the start of spring break, her first one for which she was legally able to drink. Her friends had gone town to Saucers to relax together before spending the two weeks of spring break apart. The bar had surprise specials on some rather high alcohol draft beers. Eight pints of creme brulee stout later, and Sophie was a mess in a blue dress, passed out next to the porcelain throne. She was in no state to detect the bubbling and sloshing sounds emanating from her toilet.
A glistening rounded front of the creature topped the lip of the toilet bowl and plopped to the floor. The three small tentacles projecting from it's rear slithered and propelled it across the floor towards the greatest concentration of the scent.
Sophie grunted and rolled over as she felt a cold wet sensation against her thighs, though her severe intoxication prevented her from regaining consciousness. The creature honed in on her anus, and it's lubricated body slowly pushed its way inside the helpless girl. As Sophie slept off her night of excess, the parasite began bonding with it's host.