First Mentioned: IPTSF Text 54
Maya Calendar was a Predictamancer in service to the Side of Haffaton. She croaked long ago.
Maya Predicted that Jillian, specifially, was Fated to croak the Ruler of Haffaton.IPTSF Text 54.
Olive is aware of this Prediction and worried about it, as she is named Heir Designate; if Judy, the current Ruler doesn't die by Jillian's hand it will mean that Olive will be the one to croaked.
Real World References
Her name and discipline are references to the Mayan calender, which ends on December 21, 2012. Some interperet this end as a prediction of the end of the world or a time of great change and spiritual/psychic awakening.