Theory:

INTRUDER: Keep it to yourself, and just answer my questions. You live here alone? Well, do you?
 
GERRARD: I’m sorry. I thought you were telling me, not asking me. A question of inflection; your voice is unfamiliar.
 
INTRUDER: (with emphasis) Do you live here alone?
 
GERRARD: And if I don’t answer?
 
INTRUDER: You’ve got enough sense not to want to get hurt.
 
GERRARD: I think good sense is shown more in the ability to avoid pain than in the mere desire to do so. What do you think, Mr— er—
 
INTRUDER: Never mind my name. I like yours better, Mr Gerrard. What are your Christian names?
 
GERRARD: Vincent Charles.
Explanation:
 
When Gerrard began to tell the intruder the story about himself, the latter rejected it. Answers to his (the intruder's) inquiries were all he wanted and not a story from Gerrard. He began asking Gerrard questions, the first of which was whether or not Gerrard lived alone in his cottage.
 
Gerrard explained himself by saying, "I'm sorry. I thought you were telling me, not asking me." The line is a reference to the intruder's dialogue from the previous chapter: "Now, then, we'll have a nice talk about yourself". When the intruder had said that they'd have a little chat, Gerrard assumed that the intruder had wanted him to begin talking about himself rather than answer the questions he was asked.
 
He further explained by stating how unfamiliarity between the men had caused Gerrard to misinterpret the inflection in the intruder's speech.
 
While the above is the literal meaning of the lines, Gerrard's statements suggest that he was merely trying to evade the intruder's question. Neither he was sorry nor did he misinterpret the intruder. Moreover, his choice of words such as 'inflection' (and 'nonchalant' from an earlier scene) indicates that he is a man of letters, and he was probably trying to make the intruder feel less confident about himself, all the while trying to disarm the intruder through his wit and words.
 
On the other hand, the statement also suggests that the intruder already knew the answers to the question he had raised. And so, Gerrard informed him that the intruder's tone indicated that he did not want to hear the answers but already knew them. Gerrard's statements might possibly indicate that the intruder was already aware of Gerrard.
 
The intruder was so keen on getting Gerrard's answer and so asked him again, "Do you live here alone?" to confirm the details on him. However, Gerrard did not respond and openly questioned the intruder what would happen if he did not respond, to which the intruder implicitly threatened him that if he did not respond, he would be injured. Gerrard replied without enraging him by stating that his good sense was represented in his ability to avoid suffering rather than his desire to suffer.
 
And, he inquired about the intruder's views and addressed him as "Mr – er –" to make him known that he wanted to know his name. However, the intruder smartly responded to Gerrard by stating that he liked Gerrard's name than his own. It might be because the intruder didn't want to use his name anymore. Moreover, the line also indicates that the intruder was after Gerrard's name, and to be more specific, his identity.
 
In addition, the intruder was so eager to get all of Gerrard's information that he inquired for his Christian names. Generally, a Christian name would be given to a child at the time of his or her baptism. Accordingly, Gerrard's name was Vincent Charles.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Inflection
The way in which the sound of your voice changes during speech
2.
Emphasis
Special importance or attention given to something
Reference:
National Council of Educational Research and Training (2006). Beehive. If I Were You - Doughlas James (pp. 138-144). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.