Adopt from  Aleks13

Why, where there are three nightmares, there are four.
Mallon would be part of the family, even if he didn't look scary outwardly.
Kaaro, who had recently appeared in this world, but had already been to several dimensions, including "returning" home and leaving it with her personality and memories intact.
Anansi, the oldest in the family, who, if he tried to count his age, would refuse to be more than a hundred years old. More precisely, the oldest of his "personalities", because he was reborn, or rather, absorbed and digested by the native world more than once. This creates an unusual paradox - sometimes his memories of the same event can be different, depending on which of the shards of memory and personality at that moment will be "closer" to the main, current one.
Sekho, the youngest of them, at the same time appearing in a way that is quite natural for living beings. Such a thing is outlandish to Nightmares, as is the ability to possess a physical body without much consequence at all. The downside of this is the inability to avoid physical damage by simply disembodied. Mallon, born a Nightmare but trapped in that body within months of his appearance, is a survivor who has to gradually gather into larger, organized communities-families. How and why, he prefers not to say. But he is the most willing to make contact, taking advantage of his seemingly harmless appearance. However, getting to know the "family" repels most of them.