To a certain extent, Underworld Halflings are the most difficult opponents to deal with in the Underworld. Their lives are always filled with cunning, and they act entirely according to their whims, making it impossible to find any patterns. Just because you follow some rules, doesn't mean you can avoid the backstabbing they might do behind your back.
When you have value for the Drow Dark Elves and do not stand in the way of certain families' interests, you are safe; when you bring the precious ores that the dwarves love most, buying their goods and bringing them great profits, you are safe; when you are a fool or possess secrets that the Brain-sucking Demons urgently want to know, you are safe; when you have sharp claws and a strong shell, then even when walking in the nests of Horror Claw Monsters, you are safe.
But you will never know how to be safe when walking among Underworld Halflings.