While the (generally non-consensual) union between a nymph and a fiend typically results in the birth of a half-fiend, about one in 20 such incidents can instead lead to the birth of a forlarren, a unique creature distinguishable from either nymphs, fiends, or half-fiends. Most nymph mothers die while giving birth to a forlarren, and those who survive and attempt to raise the child in a loving environment are often faced with the forlarren's inherent evil, which typically only leads them to resent and eventually murder their own mother.
Forlarrens reach adulthood in only a single year, and can theoretically live for centuries. However, due to their violent lives most perish before they turn 10. Most are female, and only a few are capable of conceiving children of their own.1
Forlarrens are cast out from both fey and fiendish society, which leads to a lonely life spent consumed by hatred of all around them, including themselves. They manifest this anger in single-minded, violent aggression toward others, but should they kill another living creature, their nymph heritage can inspire overwhelming, almost nauseating amounts of remorse. Their erratic behavior makes befriending a forlarren difficult, even for others of their own kind.1
Like many fey, forlarrens have a natural resilience against weapons not made of cold iron, but they share few other traits with their nymph mothers. Instead, they generally have magical spell-like abilities linked to their fiendish fathers.1