First, SPOILERS! ---------- The Book of Sorrows is quite the read. In it we have a wealth of knowledge about both the Hive and the Darkness. However, this post is to say why Oryx may be hanging around (in some form or another) AFTER King's Fall. Book 50 says, "[i]If my Court and my throne can be beaten, if I am confronted in my throne, if I am defeated there, then I will die. My work will end.[/i]" This would lead to the assumption that Oryx can be permanently put down and we are going to end The Taken King during the raid...or are we? In book 36, Oryx to become the Taken King kills his sisters to gain their power to kill the worm Akka. It is said of their deaths, "[i]These were true deaths, for they happened in the sword world.[/i]" But what happens a few books later? His siblings rise again, "[i]At the end of those hundred years he killed the Ecumene Council on the Fractal Wreath, and from their blood rose Xivu Arath, saying, 'I am war, and you have conjured me back with war'[/i].” The same thing happens when he practices treachery, his other sibling returns, "[i]But he drove the Dakaua Nest into a trap, and they were made extinct. From their ashes rose cunning Savathûn, saying, 'I am trickery, and you have conjured me back with trickery.'[/i]" What does this mean? We know Oryx is the personification of curiosity and the search of Knowledge from Book IX. If the same is true about his siblings, his dying a true death may not be so permanent. The Calcified Insights imply Oryx is ready for this outcome: [i]And armed thus with my past, and my future, and my present (which is a weapon, a weapon that takes whatever is available, a weapon bound to malice), they will mantle me, Oryx, the Taken King. They will become me and I will become them, each of us defeating the other, correcting the other, alloying ourselves into one omnipotent philosophy. Thus I will live forever. I’ll make sure.[/i] Go read the grimoire for Oryx:Defeated. Oryx is congratulating you on you taking his power. This is and was his belief structure, that the powerful conquer the weak and this is existence's truth (peace is a fallacy of the traveler, "War is Love"). Oryx's nature is to seek curiosity, and in doing so we could become like him, diving too deep into power we don't understand and becoming him OR the seeking of that knowledge so deeply will be what brings his personification back. Either way, Oryx through The Deep(darkness) has become a personfication of curiosity and has done what the Vex have not - he has become a staple of existence as are his siblings. I do not expect the King to stay down forever, or at the very least his mantle to remain vacant.