Su Hong's sensitivity to his question made Li Yan recall that earlier, in the main hall, after he had pieced together what might be going on, he had noticed that whenever Su Hong uttered the words "Chief Altar Master," her voice was far from natural.
Su Liuyun, on the other hand, had shown no such abnormality. Li Yan had already understood that it was because she had experience in the "Gui Xi Army." That should have been the form of address used between superiors and subordinates in the military.
Su Hong had merely traveled through various realms to temper herself, so she had not had many chances to face the Chief Altar Master before. Even after returning, she likely still retained her old habit in how she addressed him.
But because Li Yan had been standing at her side then, Su Hong could only deliberately avoid it, making her speech sound somewhat unnatural.
By asking that question outside the main hall, Li Yan had deliberately wanted to arouse Su Hong's suspicions. Sure enough, she had been extremely sensitive to it.
By that point, Li Yan had almost confirmed the Chief Altar Master's identity! Yet he was not angry that Su Hong had not told him these truths.
If it had been Li Yan himself, with a prominent background and his low-key personality, he likewise would not have wished to reveal his true origins. He had always felt that hiding them was not enough; how could he possibly flaunt them everywhere?
Moreover, Su Hong was a peerlessly beautiful woman. All sorts of people with ulterior motives would want to approach her, so she would only become more cautious. While she had never revealed her identity, she and Li Yan had maintained a good relationship.
Later, although the two of them became