This type of peculiarity is, "activated," by the peculiar themselves, such as Emma Bloom's pyrokinesis. Activating these types of peculiarities can attract the attention of any hollowgasts in the area. Other examples of peculiars with this type of ability would be Enoch O'Connor (similar to necrokinesis), Fiona Frauenfeld (agrokinesis), Althea (cryokinesis), and all ymbrymes (temporal looping). Hydrokinesis (water manipulation) was mentiond by Emma in The Library of Souls.
This type of peculiarity is on all the time. The user cannot control it, and therefore cannot, "activate," it. It is unknown if these peculiarities attract hollowgasts, unless the peculiarity is directly related to them, such as it is with Jacob Portman. In the beginning, his ability to sense and see hollowgasts is out of his control, although towards the end of Hollow City, he develops a stronger connection with them, which he can choose to "activate" or not. Another example of this is Olive Elephanta, who floats constantly. If not for her weighed shoes, she would float into the sky and never come down. Millard Nullings is always invisible and it is implied that he slowly became invisible.
Physical PeculiaritiesEditPhysical peculiarities are abilities that are built into the body, such as Claire Densmore's backmouth or how Hugh Apiston's body has adapted to store bees without harming himself.
Internal peculiarities consist of powers that locked within the mind, like Jacob's ability to see hollows or Horace Somnusson's prophetic dreams of the future.
These peculiar's are probably known to have elemental peculiarities such as Emma's pyrokinesis and others that are still unknown.