I ran across this on the Chicago Manual of Style site:
You can see that they don’t favor capitalizing pet names. Example: Please close the door, darling.
When helping others edit, this is the tactic that take (the tack that I take?). However, I DO see a lot of caps used for pet names. I would use capitals for titles, like this:
I’m coming home tonight, Mother.
Will I live or not, Doctor?
Or for pet names consistently used instead of actual names:
Oh for cryin’ out loud, Loopy, you know you can’t jump your motorcycle over the Grand Canyon.
But not for a common endearment, as in the second paragraph.
The question in the link mentioned “down” styling. I’m wondering just what this means. Any ideas?