Board Thread:Lore Discussion/@comment-2165692-20161018043733/@comment-7673575-20171024173520

Alright, enough! Time to set some facts into stone.

"Exhausted and near the end of my spells, I parlayed with the wyrm, offering it life if it would share its secrets. Haughty to the end, it agreed to one secret for one life. I asked for its name, but it told me it would rather die than surrender that."

- Brarilu Theran, Twin Secrets

This by itself proves that a name of a dragon holds certain power over him/her, and as such revealing it to another being is a bad idea. Nahfahlaar could have easily have changed his name to Nafaalilargus simply because of that, but there are some other reasons that may be it:


 * By that point in Third Era, Dovahzul was damn near dead as a language, with only a few words (such as "Evgiir Unsalad" ) being in uncommon use, and almost exclusively in Skyrim. It is almost certain that Imperials were merely unable to pronounce "Nahfahlaar", or it sounded more like "Nafaalilargus" to their ear.
 * Seeing just how many languages, both fictive and real, contain silent "h", Imperials may have simply mispronunced  "Nahfahlaar" as "Nafalar", which then became a base for "Nafalilargus".
 * Tiber Septim swore to protect the dragons that served him. First logical step: assign them fake or distorted names so that their real names remain unknown to all but him (because then, no one would be able to harm them or turn them against him with that knowledge).
 * Out of lore reason - Lore that dragon names are each made up out of three words of Dovahzul was not yet invented when Redguard was produced.

As for the argument that Nahfahlaar died 500 years before Nafalilargus was ever even mentioned: dragons are biologically immortal, which can be seen in this excerpt:

"There is no credible story of how dragons came to be. According to dremora that the College of Whispers have "questioned," they just were, and are. Eternal, immortal, unchanging, and unyielding."

- Torhal Bjorik, There Be Dragons

Furthermore, it is as LeFibS said: Nahfalaar was a coward who hid behind mortals for protection. When his lord was terminated, he ran away. Since he did pretty much nothing but hide, he could have taken on a different name because those are usually part of the hiding package. And what better person to hide behind than a friggin Emperor of almost entire Tamriel, who is also a Dragonborn!

True, as Nahfahlaar was a coward he wouldn't make a very good guard. But let's face the facts: he was one of the last surviving dragons, and quite possibly the only one known at the time. That alone is enough to elevate his status to legendary. His very appearance, and perhaps some boasting and intimidation (and we've seen that Nafaalilargus was a silver tongue) would've been enough to scare almost anyone away.

As for Numinex, and his queer name: again, his real name may have been lost in centures or simply mispronounced, hailing from a near-dead language.

It is also quite possible that his true name was Numunnax, meaning "Now-Man-Cruelty". After Olaf captured him and made him his slave, it is quite possible he purposely changed his name to Numiinex meaning "Now-Eye-One" (yes, I know that "gein"  is the Dovahzul for "one" but "nex"  could just as much be a synonym, as "single" is for "one") as a way of saying "I now belong to One-Eye" to psychically torture him and break his mind, ensuring the dragon's amenability (kinda like what Ramsay Bolton did to Theon Greyjoy by renaming him into "Reek", and did that to that extent, that Theon was actually convinced that his name was indeed Reek). Due to this, accompanied with (quite possibly) claustrophobia and imprisonment, Numinex lost his mind, and even forgot his own name, calling himself his assigned name from that point on.

"I used to visit him from time to time. Nearly crazed by loneliness and captivity. . He did not even remember his own name."

- Paarthurnax during The Fallen

And there you have it. If I missed something, be a dear and let me know.