"Answers" mark 3.

[Kicha]

I've considered this idea, that we are tempered by Hydaelyn. It would explain why the other primals can't temper us, and iirc, Garuda does say something akin to us being touched by Her. We do seem to do whatever it is the giant crystal asks of us. Sure, we seem to have more freedom than others who have been tempered, but maybe that's the difference between a powerful entity like Hydaelyn tempering us and a lower primal. Lower primals rely on brainwashing. Very straightforward. Hydaelyn has more power, so she doesn't let us know we're tempered, but simply guides us and nudges us in the right direction, all the while we're convinced that we've got our own free will and are doing Hydaelyn's bidding because we WANT to....

[Alenore]

I've considered this idea, that we are tempered by Hydaelyn. It would explain why the other primals can't temper us, and iirc, Garuda does say something akin to us being touched by Her.

Amal'jaa priest : "Your soul already belongs to another!? Yes, that is the only explanation!"
Ifrit : "Forsooth, thy frail mortal frame can serve as vessel to the blessing of but One. Yet I smell not the taint of another upon thee... The truth of thine allegiance waxeth clear - thou art of the godless blessed's number. The paragons warned of thine abhorrent kind. Thine existence is not to be suffered."

The Amal'jaa priest seem to think we've already been claimed by someone. But, Ifrit doesn't feel like we've been, and that in truth, our soul just cannot be claimed, and that it's a crime in itself.

From that bit of text, I take that the Echo somehow protect us from being claimed/tempered/touched/stoned (hi kobolds!), and not that we've already been tempered/touched by someone.

[Morningstar1337]

I've considered this idea, that we are tempered by Hydaelyn. It would explain why the other primals can't temper us....

I had the same idea. Though my version og the theory keeps some fo the free will aspect. As for how the PCs were tempered, I think the Echo is a form of temepering.