Eingyi

Eingyi was once a pyromancer from the Great Swamp, but his experiments with poison and toxic pyromancies caused him to be branded a heretic and cast out. He traveled to Lordran and eventually reached Blighttown, where he became infected with a mysterious plague referred to only as the "Blightpus". Quelaag's Sister eventually discovered him and, against the wishes of Quelaag, sucked the Blightpus from his body to cure his illness. This kind act left her body in a sickly, crippled state, but it also earned Eingyi's undying loyalty, despite his inability to communicate with her.

Eingyi can be found behind an illusory wall near the bonfire below the second Bell of Awakening in Quelaag's Domain. His body is covered in a mass of parasitic eggs laid by Quelaag's Sister and carried by Eingyi out of his devotion to the "Fair Lady". He is initially distrustful of players due to their lack of eggs, and he will ask whether the player is a servant of his Mistress. Answering "yes" is the only way to speak to Quelaag's Sister and join the Chaos Servant covenant.

Even after joining the covenant, Eingyi will still not completely trust the player character and initially only sells the Servant Roster, a list of all current members of the Chaos Servant covenant. However, should the player become infected with parasite eggs, Eingyi will be very pleased and begin selling his unique pyromancies and Pyromancy Flame upgrades, as well as Egg Vermifuge items which can be used to remove the parasitic eggs. Eingyi will also express his envy towards the player if they equip the Old Witch's Ring and speak to Quelaag's Sister, as he was never able to converse with her himself.

Killing Quelaag's Sister will cause Eingyi to become hostile and attack the player in an attempt to avenge his mistress.