My Dear Fellow
Holmes’s and Watson’s pet names
(How Holmes and Watson call each other)
Watson’s for Holmes
“My dear Holmes”: 16 times
“My companion”: over a hundred times (I’m refusing to count any further)
Holmes’s for Watson
“My dear Watson”: 94 times
“My dear boy”: two times (this means exactly what it sounds like)
“My boy”: nine times
“My dear doctor”: two times
“My Watson”: three times
There is an awful lot of possessive pronouns here, if you start to think about it…
Could they appear more married if they tried??
('My companion' shows up at least 146 times in canon. I'm not sure how many times it happens between who and would have to check, but confident that their count of it being at least 100 times that Watson referred to Holmes is likely accurate.)
ことり(@kotoriih) discussed about how, in Granada, Watson calls Holmes by 'old fellow'.
https://twitter.com/kotoriih/status/1066184657530540032https://twitter.com/kotoriih/status/1066184657530540032


In both Granada 'Old fellow' is used while Rathbone uses 'Old Chap'.
I am not sure if Granada ever uses the canon correct term of 'My Dear fellow'.
https://twitter.com/kotoriih/status/1066184657530540032
In the Canon stories, both Holmes and Watson refer to each other multiple times in canon as 'My Dear fellow'.
The Resident Patient:
https://sherlock-holm.es/stories/html/resi.html

The Reigate Squires:
https://sherlock-holm.es/stories/html/reig.html

Holmes uses it for Watson more then the other way around, but Watson does use it a few times like in The Reigate Squire when consoling Holmes and asking him to take a rest.
It seems noticeable and significant to me that adaptions consistently soften the terms of endearment that Holmes and Watson canonically use for each other when speaking and referring to the other. Instead of possessive terms frequently used 'My ---', more formal words and terms of casual friendship are used instead.