Originally before he learned of all the details, Bai Long wasn't much interested in whatever it was that the Empress and her predecessors were hiding underneath the capital city.
But, the more be heard about the details the more interested Bai Long became in whatever it was that they were hiding.
At the same time, he learnt that none of the Sword Fairies have a name.
No, they weren't born and grew up without their parents giving them any names. Instead, once they were chosen to be the Sword Fairies by the Empress, they no longer had any names and would instead only be called by their titles.
Thus, the Sword Fairy after being called by her title for so many hundred and maybe a thousand years no longer even remembered what he actual name was. And this was most likely the same situation the other four of the Five Fairies were in as well.
Seems like the Ice Phoenix Empire doesn't treat the five guardian pillars good enough.