Garuda's interesting in that she's basically the only primal for which we know the original story that inspired it, and that isn't accurate. Like, at all. The Ixal have been playing a five thousand year long game of telephone with this story, and the facts have... drifted. Rather considerably. Rather different from an example like Thordan or Good King Moggle Mog XII, where as far as we can tell the myth they summoned from is more or less the truth of what happened.

I agree with Kage that the first part is most likely what the Ixal actually believe. You can pretty immediately see how they got some of it, but hell if I know how exactly the 'blood of the king' part wound up in there.