As the two Holy Knights talked, Incarnation Randy occasionally would nod and even guide some of their responses by asking some prompts in between to get more information. At some point in the two Holy Knights' narration, Incarnation Randy took a chance and naturally poured them a glass full of liquor.
As he did so, he grabbed an empty unused glass on the table and also poured himself some of the liquor he had poured for them. He did so in order to avoid any suspicions. However, despite pouring himself a glass of liquor, he merely took a few sips throughout the entire exchange. Furthermore, his glass was only a quarter full.
As he was still eighteen years old and considered a minor, this was his first time drinking alcohol. As a result, he didn't know his alcohol tolerance level. He also didn't want to risk getting intoxicated himself while purposely urging the two Holy Knights to drink their liquor in order to get them intoxicated. Therefore, he limited his alcohol intake.