Revelations from Patch 6.1

[Lyth]

I'm going to assume you have to actually have the Reaper job equipped for that since I had it capped but didn't see any such mention.

MSQ:

This took forever to dig up again, because it wasn't in a cutscene. The line occurs in 'A Brother's Grief' a little while after speaking with Vrtra's Alchemist, and cross-checking it with a different playthrough, it does seem to only show up if you're actively on the Reaper job, regardless of whether you've got it at max level:

G'raha: An ancient mechanism channeled the tower's vast stores of energy to open a voidgate ─ one bound to a covenant made with the Cloud of Darkness.
Once that sovereign entity was beaten back, however, the covenant was broken, and the doorway severed from its connection to the void.
Theoretically, it should be possible to reconnect the gate by forging a new pact with another voidsent... but such deals usually end in betrayal and death.

Y'shtola: You seem to have struck a bargain of your own, <playername>. Though it serves you well in battle, be aware that the beneficial nature of your “arrangement” is the exception which proves the rule.

I like seeing these little flourishes. I really wish that they had fleshed out the lore on the voidsent that you're personally contracted to during the Reaper questline. Hopefully this business in the thirteenth will give them more ways to expand on this.

...

Myths of the Realm:

This was suggested earlier, but Deryk could very well be connected to Oschon, especially given his expressed preference for 'wandering alone'. Also, if you look at the layout of The Omphalos, the wind shrine is one of the two heavens closest to the seventh heaven, and seems to be missing an associated familiar (likely the opo-opo), suggesting that Oschon will probably be part of the final tier. The other one might be Water, given the little assassin fry hanging outside of the shrine. It could be Ice, but the other 'blue' element has a dwarf rabbit outside, which doesn't seem particularly aquatic.