Insanity is a mental disease that removes the ability to perceive reality. A person that is insane is unpredictable, dislocated from time and space on a mental level. They act in a fashion that is unusual for a normal person and their actions are often out of place, erratic and sometimes aggressive.
Insanity is a common flaw found in Jester, after they learned that imperfection is an omnipresent mannerism in the Universe and that it is impervious to change.
A character inflicted with Insanity starts to go mad. They fall into illogical patterns and change them in random intervals. This can happen as often as each breath takes time, or it can remain with days of no noticeable change.