I work as a language editor (copyeditor). I sometimes need to edit novels as well. Here is my doubt that has been nagging me for sometime now. I have typed an arbitrary sentence to present my case:
"Yes, Mr. Andre, I shall look into the matter," George replied.
I would like to know whether such titles as Mr., Ms., Dr., etc., should be expanded or left as such within dialogues.
When they are part of the name, use the short form, though Professor and military ranks are normally written in full in dialogue. In British Englishwe normally write the short forms without a full stop (period.)
If the words are used on their own, then we use the full form:
"So, Doctor, is it serious?" asked Mary.
"Spare a copper, mister?" whined the street urchin.
Note that there are no expanded forms of Mrs or Ms.