The parasites are a group of extraterrestrial organisms that infested the space-faring alien race's transport ship, causing it to crash in the Zagros Mountains and transforming them into vicious monsters with a vulnerability to ultraviolet light and a hunger for the adrenaline found in blood.
These parasites infect their hosts and will reside inside their body until they eventually kill them. After killing their victims, the parasites reanimate and mutate their bodies. An infected individual can be saved by forcing the parasite out of their body via exposure to ultraviolet light.
Millions of Years Ago
The ship of a space-faring alien race picked up these parasites during its travel. They infected the crew, creating chaos on board the ship and causing it to crash into Earth. These aliens then became the bat-like alien vampires.
A fight between the Akkadian and Gutian armies during an eclipse awake the vampires underground, causing them to flood the surface and kill or infect everyone they find. This leads to the infection of The Ancient One.
Rachel can also become infected and will transform if she was killed by the Ancient One or refuses to be cocooned. Salim offers a cocoon to Rachel to slow down the development of the parasite. Alternatively, if Eric finds out that vampires are burned in ultraviolet light, he uses a UV lamp to force the parasite from his wife. Rachel regurgitates the parasite, however it slithers off - she or Jason will give chase and then can stomp on it once one of them finds it, killing it.
In the ending, a secret U.S. government organization finds and examines several dead alien vampires and retrieves the parasites from them, as well as the fluid they use to preserve themselves - which then gains the label X-1172. If Rachel is cocooned and at least one survivor makes it back to Camp Slayer, she will be rescued and the parasite will be removed, saving her life.
|Chapter||Mechanism of Kill||Caused by||Conditions|
|Slayer||Impaled||Salim||Salim completes QTE to stab the vampire.|
|The Truce||Nick and Salim||Salim decided to kill the vampire; Nick and Salim complete every QTEs.|
|The Assault||Burned||A Vampire (Indirect)||Certain.|
|Enemy of My Enemy||Impaled||Salim||Salim completes QTE to stab the vampire.|
|Strange Aeons||Burned||Rachel||Eric allowed the usage of WPs; Rachel is infected; Rachel stabs the White Phosphorus round.|
|Stomped||Rachel||Eric is aware about the vampires' weakness and alive; Rachel is infected; Rachel survived the ordeal; Rachel volunteered to be cocooned; Rachel or Jason finds the parasite and completes a QTE to stomp it.|
|Nick||Eric is aware of the vampires' weakness and alive; Eric has a high relationship with Nick and lended him his UV wand; Nick fails Keep Calm! segment while hiding from a vampire if injured; Nick chose to retreat; Nick fails to fight the vampire on his way.|
|Semper Fi||Impaled||Salim||Salim succeeds to fight the vampires.|
|Daylight||Burned||The Sun||The protagonists survived 6 minutes of eclipse.|
|Chapter||Character||Mechanism of Kill||Condition|
|N/A - Prior to events of game||Numerous Pre-infected Vampires||Infection||Certain - Off-screen.|
|Cursed||Balathu||Whichever character that was killed last by the vampire.|
|Bloodbath||Clarice||Clarice is abandoned OR Clarice refuses to swing pass by the chasm.|
|The Horror||Clarice is brought from the temple; Clarice will always turn regardless if she is abandoned or stay.|
|Strange Aeons||Rachel||Rachel is infected; Rachel survived the ordeal; Rachel refuses to be cocooned.|
- One parasite exists as a secret in the game.
|Protagonists||Eric • Jason • Nick • Rachel • Salim|
|Antagonists||Alien Parasites • The Ancient One • Vampires|
|Supporting Characters||The Curator • Clarice • Joey • Merwin • Dar • Shepherds • Randolph • Naram-Sin • Balathu • Kurum • Pazuzu • Minor Characters|