...if Lavinny's boy looked like his pa, he wouldn't look like nothin' you'd expect
— H.P. Lovecraft, Dunwich Horror
The supernatural has lived alongside mankind since the earliest days of our species. We have warred against them, traded with them, and forged alliances and friendships. Inevitably, over the millennia of interaction, children are conceived, born with one foot in the world of man, and one claw in the world of monsters.
The strange are the not-quite-human offspring of such relationships. While stereotypically a strange child is a result of violence or supernatural coercion, that is not universally the case, and, indeed, many strange grow up knowing both of their parents. However, it's usually the orphan or the child who discovers their magical ancestry in their teenage years, who become the source of countless folktales and urban legends.
Most strange appear relatively human upon first glance, with only vague tells of some kind of supernatural ancestry: eyes an odd colour, an odd birthmark, or their shadow doesn't quite match their physical form. Most strange grow up feeling like they don't belong in human society, but even those raised among their supernatural kin usually feel ostracized for being too human.
The strange can usually manifest a limited version of their supernatural parents' abilities, but their relative lack of prowess in that area is contrasted by their human nature tempering their weaknesses. A vampire might not be able to walk in the sun without feeling its oppressive glare, but their dhampir child can.
Cambions: The descendants of demons and humans, cambions are born already half-damned. For many, that damnation manifests physically, in horrible deformities such as scaled flesh and cloven hooves. But for others, the taint is silent and more insidious, twisting their souls towards sin and corruption and inspiring these ill-fated souls to wander dangerous paths. Cambions can manifest the torments of their demonic parents, but at grave risk to their own souls.
Dhampir: The children of vampires and humans, almost all dhampirs are born from a mother who was turned while pregnant with a child. A dhampir is thus a living child born to the dead, an anomaly from the moment of their birth. Fittingly, most dhampirs are supernaturally tied to the forces of death and undeath, and they can wield versions of their vampiric ancestors' artes.
Feytouched: Born of trysts between fey and mortals, the feytouched are magical individuals who blend the raw imagination of the fey with the drive of mankind. Most feytouched are prone to flights of fancy and waking dreams, seeing elements of the fantastical bleed into the mundane world around them. With the touch of faerie magic around them, they can make use of the Old Laws and use the glamours of their fey ancestors.
Mares: The spawn of horrors are humans are fated to become monsters. Born with a waking shadow, mares must constantly struggle to keep their darkest instincts in check, lest they become the creature everyone else presumes them to be. A mare is usually born with some bestial elements, such as fangs, claws, a tail, or furred hide, further leading to their ostracization from normal human society. As a small blessing, though, mares can feed on terror like their horror ancestors, and they can twist that terror into nightmares to lash out against those who oppose them--be they predators or prey.