Griping Demons
The griping demons are a pair of demons, one an incubus and one a succubus, who can be encountered in the Bizarre Bazaar. When the player goes to the Bazaar there is a random chance that they will overhear these demons talking to each other. From their conversation, the player learns they are researchers of some kind, working under the command of the mysterious "Syrena", a part-shark omnibus who is seemingly more interested in her own pleasure than the research she's undertaking.
Once the player has encountered the griping demons, there is a random chance of finding them again, which presents the player with the opportunity to eavesdrop on their conversation, which will be a brief snippet of them discussing the negative aspects of working under Syrena. Currently, this can only be done thrice.
The incubus is described as a "curly-haired, chiseled Adonis of a man, with a bulge as over-the-top of the rest of him straining at his fashionable pants", while the succubus is only described as wearing a lab coat without any sort of clothing underneath, her nipples permanently erect and dripping with fluid that stains her lab coat and her nethers constantly drooling sexual fluid, to the point she leaves a trail of girl-slime wherever she goes, like a giant slug. The succubus notes she has been a test-subject for some of Syrena's prototype compounds, making her perpetually horny even by demon standards.
From the discussions the two have, it appears that the succubus is prone to making Syrena angry due to her incompetence, and the incubus openly suggests it's only her enjoyability as a sexual partner that has kept her from some horrible fate, noting that if he screwed up as often as she does he would have been sent to one of the factories to stoke the furnace or else fed to hellhounds.
As the two demons are only ever seen in each others company, which they seem to enjoy, it may be assumed that that the two of them are lovers, at least by demon standards.