I'm Not your... puppy?

Eos has no way to tell how long someone disappears for, or for what reason.

To be slightly more accurate - I have no way to tell h ow long someone will be gone for. Obviously I can tell how long someone was gone for, when they reappear. ie: I can only observe the past not predict the future.

To be technical, disappears and appears occur due to world transfers and name changes too, they just have corresponding appears in different places or as different names.