"It is quite possible, then, that my employer fully expects me to respond to his bantering in a like manner, and as I say, a matter which has given me much concern. But I must say this business of bantering is not a duty I feel I can ever discharge with enthusiasm. It is all very well, in these changing times, to adapt one's work to take in duties not traditionally within one's realm; but bantering is of another dimension all together. For one thing, how would one know for sure that at any given moment a response of the bantering sort is truly what is expected? One need hardly dwell on the catastrophic possibility of uttering a bantering remark only to discover it wholly inappropriate."

Stevens is thinking to himself about how his employer is always bantering to him. Stevens doesn't understand the point of this bantering and is questioning the social purpose of why Mr. Farraday banters to him like he does. He is saying he does not like talking to his employer like this. He understands having Mr. Farraday tell him what to do because he does work for him, but he doesn't understand what the point of these conversations and what they have to do with Stevens being a butler.The purpose of this passage is to show how Stevens thinks and his aversion to social interactions. The passage is presented in a confused tone. It is obvious to the reader that Stevens is questioning this and confused on why Mr. Farraday does this.