In BDSM relationships, a dominant male is often referred by his submissive counterpart as a "master", "sir" or by some other honorific. Some in the BDSM lifestyle insist that words referring to the dominant person in a relationship should always be capitalized, whereas those referring to the submissive partner should be written in lower case. While such a generalization does not adhere to the rules of the English language, I can't help but think that there are situations where capitalization is appropriate.
In particular, I am wondering whether capitalization of "master" is appropriate in the following examples, where the word refers to a specific person:
"Welcome home, Master."
"No, Master, I haven't finished my chores yet."
"My Master will be with you shortly."
I believe that the capitalization in the first two examples is correct, but not in the third. However, I am not certain about which rules apply and I'd appreciate it if somebody could shed more light on the matter.