Ananke is considered by some to the primordial source of Necessity and Fate.
What is know is that the entity is the personification of Space, the arena in which events can occur. Ananke provides the 'where' along side Chronos' 'when'. A third force, Us (aka Eros) is sometimes considered to supply the 'why'.
Knowledge of such forces is so far beyond the comprehension of mortals, and even gods. All information on the Old Ones comes from more ancient sources, usually Celestials, so can not be considered reliable.