Originally Posted by
LineageRazor
Actually, I think I read somewhere that Garuda is actually based on distorted legends of the Allagan researcher in charge of creating the Iksalions (who later became the Ixal)? Something in the Lore book, maybe? It's entirely possible that EVERY Primal has some real, historical figure behind it, but most have been lost to myth and legend.
We have direct evidence that Shiva and Bahamut bear little resemblance to their "real" selves, and Moggle Mog is likely in a similar boat. Until given other evidence, it's logical to assume that all primals work the same way; they are constructs created from the prayers of their followers who may have no resemblance to their original selves (if there even WAS an original self to begin with).
Personally, I don't think that any summoning of Rhalgr can be assumed to be the "real" Rhalgr, unless the game makes it explicit.