Board Thread:Lore Discussion/@comment-71.58.163.238-20130703034923/@comment-108.248.14.21-20131113234135

Another possible interpritation,  Paarthurnax tells us in the first encounter with him, is that he is quite fond of conversation. He may have at one point heard of Numinex's inprisonment, which may have lasted past the point which dragons where common among skyrim (a guess on my part, I'm still looking into learning more of the history) and may have went to visit him to converse in his native tongue.

If Paarthurnax had never met Numinex before his imprisonment he would be relying on outside sources for his true name, one that was either long since forgotten, or one that Numinex no longer associates with due to the disgrace of capture.

They say the sweetest sound in any language is ones own name, the details leading to Numinex's inprisonment may have been disgraceful enough that he would rather take on a slave name, than associate the events with his own reputation.

This would of course give more credence to the notion that Numinex may have cut a deal with Olaf, and through trickery got the shorter end of the stick, more reason that Olaf earned his place in Sovngarde.