Your fellow can only mention the Emptiness once per week, and will not mention it again until you have completed the quest.
You cannot call your fellow in Promyvion unless you have 33 points of bond, despite the fact that your NPC may mention this quest before you have the 33 points. The maximum bond is 30 until you finish the Past Reflections quest.
You have 45 minutes with your NPC to find at least one "???." There are a total of 5 ??? for this quest.
When you kill monsters in Promyvion, your NPC gets credit towards a quota of 30 monsters needed for the maximum EXP bonus of 1,200 EXP. Note that even Strays and monsters that are too weak count toward the kill quota.
It appears that your NPC either still gets experience for higher level kills past the quota, only gets experience from higher level kills, or has a higher quota. More testing is required.
An additional bonus is determined by which how many ???s you examine.
If you check 1 ??? and then conclude the investigation, your NPC receives a maximum of 1,500 exp.
If you check 2 ??? and then conclude the investigation, your NPC receives a maximum of 2,400 exp.
If you check 3 ??? and then conclude the investigation, your NPC receives a maximum of 3,300 exp.
If you check 4 ??? and then conclude the investigation, your NPC receives a maximum of 4,800 exp.
If you travel to both possible third islands and check all 5 ???, your NPC receives a maximum of 5,700 exp.
You must answer "Not yet." after checking each ??? to continue finding ???s before the 45 minutes run out.
When you find each ??? and check it, you get the option to end or continue the investigation. If you choose to end it, you also have the option to warp back to the entrance of Promyvion. After that, your Fellow gets the experience points for the monsters you've killed, with a bonus added depending on the number of ??? you examined for the quest.
Return to a Rendezvous Point in any city and call your fellow to receive a Tactics Pearl, which allows you to summon your fellow every 3 minutes.
If you investigated to at least the second island, your fellow also gives you a food item based on his/her personality, as in the Mixed Signals quest (must have quest completed to receive food item).
If Japanese Midnight passes after you've called your NPC at the Rendezvous Point in Promyvion and you were unable to finish, you must exit Promyvion and come back before calling your NPC at the Rendezvous Point again.
If you lose your connection you fail the quest; your fellow will be gone when you log back in.
If you enter the Spire of Dem/Holla/Mea on the final island, you fail the quest.
Calling your fellow inside Promyvion and the experience bonus gained upon ending the investigation do not add any Fellow Points with Ajahkeem.
Your fellow cannot level up as a result of the EXP bonus gained upon completion of this quest.
However, experience you get from killing monsters during the climb does count toward fellow points, and your fellow can level up while killing monsters during the quest.