Angel's question was not without reason.
Since they entered the Underground Labyrinth, along the way, they encountered a lot of emblems related to the Baiyuanians, such as the Snake Entwined Staff and Snake Entwined Cone. Moreover, most of them were found in the ruins of laboratories.
From these small details, it can be glimpsed that a thousand years ago, Naraku City seemed to have some connection with the Baiyuanians.
However, at this time, Angel hadn't linked the Box of Cicia with the Baiyuanians.
It wasn't until Cicia wanted to pull Angel into the "Dark Space," but was blocked by some power in his left earlobe. Coupled with Cicia's curiosity about Angel's left earlobe and her previous mention of a "familiar fluctuation," it made Angel wonder if Cicia had sensed... the Primeval Flame?
And just now, Cicia's "dissatisfaction" with Angel's answer confirmed Angel's guess that the "familiar fluctuation" Cicia mentioned indeed referred to the Primeval Flame.
