Tiamat. That is all.
Look at the effect she had on Dany. Extend that across centuries. It does stuff to your morality. Yes, it requires one hell of a good explanation, but I'm willing to listen. And if Dany + Malarys are able to agree on her being a potential rehabilitation candidate, hells to the yes am I jumping for it. And no, I don't see that as likely, but you never know. No one expected Dany to steal concept Cleric-hood from Tiamat, after all.
Why are you assuming that they were in contact with Tiamat for centuries? There's pretty much zero evidence of that. If that were the case then Dany would have been given a quest to go to Essaria to wake them up. But we didn't, instead we got a quest to do her bidding in Mantarys, probably to give her the Abyssal Gate and do something with Amrelath for her. Far more likely is that Tiamat divined places we've been, discovered the sleepers,
then got the clerics.
Hell, while we were there the first time, Dany would have sensed any connection to Tiamat. She is
super perceptive about that sort of stuff. She came up with nothing.
Anyway,
@Artemis1992, made the questions considerably shorter. I didn't feel the need to go so far as to stick to only yes/no questions, so I made questions that would only need one or two words to answer instead.
1. Does Tiamat have more clerics aside from those awoken in Essaria?
2. If yes, does Tiamat have clerics capable of the sixth circle of magic and beyond? If so, how many?
3. If no, does Tiamat have clerics capable of the fifth circle of magic and below? If so, how many? (continue to ask yes/no questions until we get exact number of all clerics and their strength)
4. Does Illyrio have mages capable of the sixth circle of magic and beyond? If so, how many?
5. Does Illyrio have mages capable of the fifth circle of magic or below? If so, how many? (continue to ask yes/no questions until we get exact number of all mages and their strength)
6. How many monsters do you know have been conjured for the Golden Company?
7. Are the drakes enhanced by Tiamat?
8. Do the drakes have special abilities? If so, describe them.
9. How many Abishai are with the Golden Company? What types of each color?
10. How many demons have been summoned for the Golden Company? What types?
11. Aside from the Shadow Dragon that almost ambushed us in Pentos, does Tiamat have any other powerful dragons moving as her pawns in or near Prime Material?
12. Do you have any valyrian dragon eggs?
13. Do you have any chromatic dragon eggs?
14. If yes to 12 or 13, have any of them hatched? Are you attempting to hatch them?
15. Does the captain of the Golden Company still have Blackfyre? If not, where is it?
16. Is the Blackfyre with the Golden Company?
17. Is the Blackfyre a cleric of Tiamat or her champion in any way?
18. What magic does the Blackfyre possess? Cleric? Sorcerer?
19. What guardians does Tiamat have for the Blackfyre? What mortal guardians are there independent of Tiamat?
20. Is the Sorcerer King of Nefer capable of Sixth Circle Magic or above? Third Circle Magic or above? Continue asking until you narrow down how strong he is.
More ancient lore is good.
Speak with Dead says hello.