So this might seem a little out there, but bear with me. I'm convinced that Eris is secretly a pawn for Savathun. Now before anyone posts "Eris hates the Hive, she'd never WORK for them", I'm not saying she's a willing one. Here's what I'm thinking: So we know Eris is the sole survivor of her team's failed raid against Crota (Technically Toland survived because he had his own Ascendant Realm, but for all intents and purposes Eris is the sole survivor). But we never learn (To my knowledge anyways) how she escaped, only that she "crawled out". We also know thanks to the Grimoire that Toland, and presumably by extension Eris and the surviving members of their fireteam at least made it to Ir Yut, so they at least entered Crota's realm. Now, we are led to believe Eris hid from the Hive, slowly working her way back, but that raises several curious questions. How did she hide? Did she lose her Ghost, and if so is that what forced her to learn Hive magic? How did she learn this magic? Where did she pick up her rock? While there are several possible answers, here's what I think. We know it's possible for Hive to travel between Ascendant Realms (Ir Halak, Ir Anuk, Malok for example) If we take into account Savathun and her cunning nature, wouldn't it make sense for her to plant agents of her own within each of the Ascendant Realms she can (Malok is evidence she's done this at least once). Now let's say she had an agent in Crota's realm, one who reported to her Eris's failed fireteam. In this hypothetical scenario, here's what Savathun could have done. She could have retrieved Eris and brought her to her own throne world. There she could have tortured/brainwashed Eris into becoming her personal agent, "gifting" Eris with her eyes and her rock through which she could whisper her orders. There she would feed information to Eris to help the Guardians kill Crota. But why would she do that you may ask? The simple answer is because it's the ultimate win-win for her, an ultimate act of pure cunning. Remember that when the Hive run into an enemy they can't overpower through pure strength, they instead "infect their weaknesses". And remember that Savathun has had her eyes on Oryx's strength ever since he gained it. But she has yet to succeed in overpowering him, so according to the Hive way, she instead infects his weakness. Crota, specifically the tribute Oryx obtains from his son. Familial love aside, Oryx depended on Crota providing him tribute to feed his worm. Though Oryx had many sources, Crota was one of his largest. Indeed, when Crota died Oryx could feel it. The Oryx, The Taken King Grimoire opens up with: Where is my son? Where is Crota, your lord, your princely god, your godly prince? Tell me no lies! I feel his absence like a hole in my Stomach. Where once his tender tribute whetted burrowed mouths, Now only hunger remains. Hear me, O waning stars, O tattered rags of Sky — I will stopper up this tearing gulf With vengeance. Savathun also surely knew how important Crota was to her sibling's survival, because despite his tremendous power Oryx still relied on tribute to survive. Sure she could just as easily destroy Crota herself (At least, we can assume so), but that would only make her a target for Oryx's wrath. Why not instead use a shared enemy instead? Savathun sends Eris back to the Tower, feeds the Guardians all the necessary information to weaken and even kill Crota. Worst case scenario, her plan fails and Crota kills them all. Now the Hive can kill the Traveller once and for all (At the time the Traveller was still dormant). Not a bad outcome for her all things considered. Instead, the Guardians kill Crota, weakening Oryx and drawing the wrath of the Taken King. Now comes the next step of Savathun's plan. Oryx himself arrives, so Savathun does the same thing. Feed Eris information on the Taken, how to invade Oryx's realm and kill him. Worst case scenario, everyone dies and the Hive get the Traveller. What happens instead? Her brother dies, opening up the way for her to claim the throne, become the Taken Queen. The end cinematic shows Eris taking a tablet from Oryx's sword, talking about "accepting her fate" to someone she calls "My Queen". Now most assume she means the Awoken Queen, which is easy to see considering the Queen seems to be speaking to Eris at the beginning of Taken King. But reading the Grimoire shows evidence the Queen herself served some darker power, specifically Skolas calling her a "Light snuffer. Dark Binder." And with the Taken presence in the Dreaming City, along with Savathun becoming the Taken Queen, maybe Savathun was that power. And here is the last bit of potential evidence of Eris being an agent for Savathun, and that is Savathun gaining the Taken powers. In Verse 3: 8 of the Book of Sorrows titled King of Shapes, it describes how Auryx (Later to be renamed Oryx) killed the Worm God Akka and learned the secrets of how to commune with the Deep (or Darkness), and he wrote these secrets on tablets which he kept with him. And what does Eris retrieve at the end of Taken King? An artifact of Oryx's. A tablet. Eris then left. And before long there was a new Taken ruler. What does everyone think?