#parasitisexual

-The most prominent species is the keyhole larvae, a predatory type of worm that leaves a keyhole shape on its hosts. The keyhole larvae starts incredibly small at a quarter of a centimeters width with a single centimeters length. While known as predators they are incredibly vulnerable when not inside of a host. They have thin sticky skin and a dual mouth full of tiny razor sharp teeth that secrete a venom with numbing properties. They tend to latch onto the belly buttons of humanoids, chewing through them to enter the body. To ensure the host doesn't notice their intrusion the larvae's venom stimulates clotting which leaves behind the distinctive keyhole like shape. Their grip is impossibly strong making it dangerous to attempt pulling one out after its has already started burrowing. Tugging a keyhole larvae will cause it to vomit and infect the wound, posing additional risks to the host. This infection has been known to form sepsis incredibly quickly and commonly results in fatalities. Once the worm has made its way into the body only then you can try and kill it by ingesting various acidic foods, compounds, and/ or medicine. Some people have found that excessive exercise helps kill the worm however surgery is a guarantee regardless of method. The time to get rid of the worm is short as once it's latched onto an organ it is nigh impossible to separate from its host without losing said organ.

The keyhole larvae usually starts by attaching itself to either the small or large intestine, biting the side of it and chewing a hole that connects the organ to its mouth. It then allows food to pass through normally while sucking up excess nutrients. Not enough to damage the host but enough to help feed the worm's growth. As it grows it begins to eat at the organ little by little, enlarging until its dual mouths split to form a passageway. Each side continues the slow consumption while also allowing materials to pass through it as if it were part of the missing organ. This process continues until the entire intestine is ingested and replaced by a now giant organ sized version of the worm. Once one organ is ingested it starts to feed off of others and continue to grow in size until it encompasses the entire lower humanoid digestive system. Hosts stop passing waste at this stage as the larvae absorbs all nutrients to grow and fuel itself. The host will likely start changing in appearance, becoming sickly and losing weight, they may also complain of stomach aches and nausea but these will slowly fade out as the next step begins. Connecting itself to the nervous system, the larvae will cut off pain receptors and begin consuming the reproductive organs. This process sometimes leads to orgasms and pleasure spikes, with some hosts becoming non hostile to the worm at this stage due to psychological stress and exhaustion. All remaining internal organs aside from the heart, lungs, and brain are consumed and the host is now fully dependent on the larvae to survive. The host can continue living and functioning as a human but with decreased stamina, muscle mass, and coherence. A very determined well coordinated larvae and host could return themselves to average or even peak physical performance given they have enough food to sustain them.