A theory about the Holmes stories-
Holmes never had a façade about being an unfeeling machine. He was just somewhat an introverted kinda guy (probably on the spectrum). Watson had only made it up to save him from public suspicions, etc.
Just look at the way Watson describes Holmes in A Study in Scarlet. The first time they met, the first case they ever solved together. He was extra poetic about him throughout the novel.
“Ha! ha!” he cried, clapping his hands, and looking as delighted as a child with a new toy. “What do you think of that?”
It's so different from his description of Holmes in the very next story, i.e., The Sign of the Four. A stark contrast-
“You really are an automaton,—a calculating- machine!” I cried. “There is something positively inhuman in you at times.”
This type of description remains consistent in the rest of the stories, later on. (Mostly. Some incidents do give him away, but generally speaking.)
The reason might be because of this-
“Some facts should be suppressed, or at least a just sense of proportion should be observed in treating them.
Holmes had asked him to do that, himself.
I know that a lot of people already think that this might be the case but what I'm trying to say is that I don't think that The Adventure of the Three Garridebs was the first time that Watson was able to see the great heart behind the cold mask. I think Watson knew about the existence of his human side already. Canon! Watson was not oblivious. He must have known everything about Holmes' feelings. I do believe that he's an unreliable narrator. A lot of the things he says in his stories can be taken with a grain of salt.
What makes Three Garridebs so special is that it was a rare moment when Holmes being openly vulnerable and affectionate towards Watson and that moment was so intense that Watson didn't have it in himself to suppress the facts anymore.
Watson says that it was the first time ever that he saw Holmes' emotional side behind the cold mask.
In my opinion, it was only partially true. That wasn't the first time he saw it, that was the time when the moment was so intense that he couldn't find any other way to describe it in his story but the raw truth about it. That's why he made it sound like it was the first time ever that he was seeing it. I really don't think that Canon! Watson was that oblivious (unlike John Watson from BBC Sherlock).
He is the POV character in most of the stories. The narration is almost always in first person. Sometimes he describes him like he did in the whole of STUD. Or like this in some of the other stories-
We had a first-class carriage to ourselves–and laying a hand upon each of my knees he looked into my eyes with the peculiarly mischievous gaze which was characteristic of his more imp-like moods.
(The problem of Thor bridge)
Other times, he chooses to describe him something along the lines of "sentiment for my companion is like a crack in the lens, a fly in the ointment..." and so on. Holmes was even playing the violin to help him sleep in The Sign of the Four. Watson was himself the one to mention it and talk about it in that story. It becomes quite contradictory sometimes.
Which is why I think that the "cold and unfeeling machine" was not even a façade that Canon!Holmes was hiding behind. He was always sentimental and Watson knew about this. This is the kind of image that Watson just made it up for his chronicles in The Strand.
To avoid unwanted questions and suspicion from the public.
