I really enjoy the different theory's though, I like to believe that the nine are the remaining Ahamkara's, They are belived to be extinct by the tower but Grimoire does hint at them be able to defy all probability so it is possible there are some(nine) still alive. I didn't create this thread but this person explains it in much detail: https://www.reddit.com/r/DestinyTheGame/comments/3bro1r/the_identity_of_the_nine/ Keep in mind to that he talk about Xur and the Jovian's the Jovian's are linked with Europa at one point briefly so it would fit as to why Osiris went to Europa because he is obsessed with the Ahamkarra's.