On the first quest for Bad Juju, "Toland's Legacy," we're told that Toland, "a once-esteemed warlock," was exiled from civilization for his obsession. In the grimoire card "Crota's End," Eris Morn finds Toland after his exile and enlists him to fight Crota. Toland tells her that Crota is a shadow in their world, and that his real being exists in an alternate dimension. Being that the only way to kill Crota is to enter his dimension and kill him there. Eris Morn and her fireteam, including Toland, enter the Hellmouth. In the grimoire card for Ir Yut, chronologically the last time we've heard from Toland (I could be wrong), it is made apparent that Toland joins Eris' fireteam to find Ir Yut and hear/learn her song of death. He's curious as to how her song is death to those who hear it, but she's somehow immune. He speculates that Ir Yut crafted the song for Crota and she uses it to pin Crota to the fabric of life and death. As far as I know, there is no hard evidence relating to remaining member's of Eris' fireteam after they meet with Ir Yut, only frequent references to her being the lone survivor. She was able to survive alongside the hive using methods taught to her by Toland. In the flavor text for the warlock bond Emerald Light, Toland says "They'll believe you are one of their own. And that is the only way." Toland gained this knowledge before they ever entered the Hellmouth, and conceivably survived alongside Eris if he wasn't killed by Ir Yut's song. It could be that Toland was killed by Ir Yut, was turned into the ash and dust that the hive are made of, and then took on a new form. It could also be that Toland is still trapped in Crota's dimension and like Crota, has taken on a shadow form outside that dimension. It could be that Toland's methods for co-habituating with the hive were more radical than Eris'. Maybe the inky blackness that streams down Eris' face consumed Toland's body entirely. It's also possible that Toland succeeded in learning Ir Yut's song and so he walks the line between life and death. "We came up from the dust and burrowed into flesh for warmth and became something new." - Xur If there's any justification to my ramblings, what remains of Toland finds its way back to Earth and shows up every week at the Tower. Nobody is able to stop him from passing through at his will, and according to his grimoire card he may have a deal with the Vanguard or the Speaker. Both the grimoire card "Ghost Fragment: Hive 3" and Eris' in-game dialog refer to the speaker having something under his mask. In the grimoire card, Eris mentions to Ikora that she's become more like the speaker and Ikora stops her before she says any more. If Toland did survive alongside Eris he would probably know the true nature of the Speaker as well, and could have arranged with the Vanguard or the Speaker to be allowed at the Tower in exchange for his silence. Hey also says some strange things if you stand next to him. For example, "My movements are to a significant degree dependent on the Planetary alignment." and the more important quote "I think the cells of this body are dying and some of the cells, in this body, began on this world. How strange to return."