Raids Lore

Ahh perfect! I do have a question. Since the first time I/we completed VOG I have become intrigued with it, there is far more lore the Crota. Here's my question though. What is Atheon protecting? If the definition of Atheon's name and many theories are to be believed, the Vex within the Vault are at odds with the majority of their Vex brethren/ selves. If the black garden was being protected just as carefully and the prize they worshiped within considered so important, what could the Vault contain?? What is within the Vault? (As I see it we as players only reached the vault's entrance. To explain, the Templar guards the vault's physical tether, it's bridge if you will to regualr space an time. Past that we find the first security measures with the Gorgons and a puzzling traverse to the Vault's true entrance (the Vex would not need any of these measure as they can teleport so who's benefit are these for?) And upon acquiring the "key" so to speak Atheon is summoned to halt our progress) So, what's behind Atheon? There is an archway leading somewhere. Is the true Vault within? Why is there a convenient hole allowing us to descend from the Templar when the Vex clearly would not require it? Some will likely say it was created by the original fireteam but it seems unlikely they would by chance open a direct path descending to the Gorgons. Some would say logicly it allows us to progress, and find the hidden chest (if you kill the Templar without allowing him to teleport), but it would have been just as easy for a gaye to open allowing us to teleport as the Vex would. Lastly there is a solitary transfer gate across the casum opposite to what I believe is the entrance to the Vault, I wonder what it's doing there??