Enola Holmes sued due to giving Sherlock “copyrighted” emotions

The complaint reads:

"When Conan Doyle came back to Holmes in the Copyrighted Stories between 1923 and 1927, it was no longer enough that the Holmes character was the most brilliant rational and analytical mind. Holmes needed to be human. The character needed to develop human connection and empathy."

This seems surprising given:

"I fear that it is at a cost which will give pain to my friends, and especially, my dear Watson, to you."

     - The Final Problem (1894)

"“My dear Watson,” said the well-remembered voice, “I owe you a thousand apologies. I had no idea that you would be so affected.”

     - The Empty House (1903)

“Upon my word, Watson!” said Holmes at last with an unsteady voice, “I owe you both my thanks and an apology. It was an unjustifiable experiment even for one’s self, and doubly so for a friend. I am really very sorry.”“You know,” I answered with some emotion, for I have never seen so much of Holmes’s heart before, “that it is my greatest joy and privilege to help you.”

     - The Devil's Foot (1910)

That headline and article view is really not quite getting the point.

The estate's argument is that the Sherlock character from the later stories is significantly different from the earlier one by the change in emotions. Which sounds kinda-sorta reasonable, though I'm not a legal expert and it doesn't seem clear-cut. Characters are, however, copyrightable.

the Doyle estate argues that, while they admittedly lost the copyright to all of the Holmes stories written before 1923—i.e., most of them—into the public domain back in 2014, it’s only in the latter stories that they still have the rights to that Doyle began to give Holmes recognizable human emotions. (A reaction, they argue, to Doyle wrestling with his grief over the loved ones he lost during World War I.) Said feelings—like, say, being worried about his (non-canonical) sister Enola—are thus a new element Doyle only introduced in those later stories, which makes them trademarked elements still controlled by the family

The fact that nonsense like this legally credible in one of those things where I feel the need to scream but do not have a legal mouth to scream with. It's strange how these rich people legacy estates can seem like such parasites. Looking forward to the Rowling estate attacking all of fantasy in the centuries to come.

An interesting legal argument. The crux of this would be if the emotions on display were sufficiently similar - and idiosyncratic - to count as a derived work. Emotions are a human universal, so it probably doesn't fly to claim that any emotions are inspired by Doyle's later Holmes work. Take, by analogy, eating; if Doyle had simply omitted to mention Holmes eating until a later work, I don't think it could be argued that any depiction of him eating is derivative of that work. If on the other hand he had specifically made a point of describing Holmes as enjoying frankfurters, which he stashed in his pocket to be consumed while on the case, then this unusual behaviour could still be under copyright.

Since emotions are far more slippery than a frankfurter, this case - while likely weak - hinges on a point of literary interpretation.

Disclaimer: IANAL