"Master, the eldest and second young masters are here."
Upon hearing the servant's paradoxical words, Hudson almost thought he had sprouted two sons. He quickly reacted, understanding that the "eldest and second young masters" the servant referred to were his own elder brothers.
The advent of this messy form of address was likely due to habit. After all, when they were back at home, these were how they were referred to.
However, upon arriving in the Mountain Domain, Hudson was automatically upgraded to "master," whereas for the two elder brothers, the servant presumably followed the habit deeply embedded in his heart.
He had no time to fuss over this; it was normal for a servant to be slow-witted. If he were a bit smarter, he wouldn't be a servant, would he?
If he were intelligent, based on his merit of following Hudson for many years, he would've been promoted to a more important position already.