"The borderline personality disorder is one of the most delicate but perhaps most sinister of monsters. They gather in small swarms around their victims and use pheromones to heighten the emotions of said victim, before feeding off on the emotion itself. They feed upon any emotion but tend to favor feelings of depression.
The monster is made almost completely of a clear ice, rendering it invisible. Only the maple shaped leaf on its tail is visible to the naked eye and looks like a falling leaf. At times, when the monster gorges itself too much on any given emotion its can overwhelm them and they simply shatter like glass."