So oryx's sister is named of Savathûn and she's a traitor to oryx. She made Crota open up a portal to the vex and unleash a mind to destroy oryx. Also, according to Balwûrs (who also has that weird û thing going on) grimiore card says that she is the daughter of Savathûn and 'not bound by time' implying that she is a time traveler. What else are time travelers? The vex