Just as Sherlock Holmes loves to acknowledge his own awfulness without doing much about it — "I'm a high-functioning sociopath," he says over and over — Sherlock has kept dutifully confessing it has a woman problem without ever quite fixing it.

That might finally, with the shocking introduction of Euros Holmes at the end of "The Lying Detective," be changing. There is an unsuspected Holmes sibling. She is a woman, and her genius, however villainous, might match her brothers'.

The series, created by Steven Moffat and Mark Gatiss (who also plays Mycroft), is based on Sir Arthur Conan Doyle's stories about Sherlock Holmes, a master of detection whose social skills are as bad as his brain is brilliant, and John Watson, his dutiful sidekick. The focus of the short stories was always the mystery, the particulars of the case. Not so for the show, which covers some cases but is really structured around Holmes and Watson's peculiar, intense, and interdependent relationship.

There isn't much room for women in that dynamic. The writers try to include women in a bunch of ways; it just never works. The closer Watson's wife Mary came to becoming a fleshed-out character, for example, the bigger the threat she posed to the Sherlock-Watson bond. It was becoming such a problem that Mary was more qualified than John to be Holmes' co-investigator, in fact, that she had to die.

This is a structural flaw that Sherlock confesses to over and over and over.

In "The Abominable Bride," it offers up repeated acknowledgments of all the women the male characters (and the show itself) repeatedly overlook. "Please give her a few lines in the next narrative, Watson. That woman has the ability to starve us to death," Holmes, played by Benedict Cumberbatch, says.

In "The Six Thatchers," the villain is an elderly receptionist whose power derives from her invisibility to the big players.

Then in "The Lying Detective," Mrs. Hudson's interesting past finally pays off: She exits an Aston Martin and tells the boys once and for all that she is not their housekeeper.

Finally, of course, there's the big reveal of Euros at the end of the last episode. That the supervillain turns out to be a woman who played three different roles — and she could because we were so focused on the feud between John Watson and Sherlock we didn't even realize it — is an exceptional reveal and a stinging indictment of how basically uninterested we are in the show's female characters. "Hey!" the show is practically screaming, "we have an issue with women! We know!"

But confessing is not the same as making amends.

In the past, acknowledging Holmes' selfishness and egotism didn't stop the show from reverting to it and celebrating it. See, for example, sequences in which Holmes texts his way through Rosie's christening and tweets as he's being exonerated for murdering Magnussen — Holmes is incorrigible and his flaws are played for laughs.

Similarly, Sherlock's meditations on how completely it failed women didn't stop it from backsliding into the men it ultimately finds more interesting. That includes the villains: Even the creepy suffragists in "The Abominable Bride" turned out to be — in some unexplained way — Moriarty pawns. Holmes' centrality is absolute. Every fact in history, including an entire political movement about women's rights, boils down to his feud with a fellow man.

The reason for this is partly that Sherlock is a little too in love with Holmes, and has linked that love to his awfulness. It's baked in. It is, secondarily, so heavily invested in Holmes' relationship with Watson that there simply isn't space for the women to whom the show pays lip-service. This is the story of two men, period. And yeah, sometimes that really stinks.

But is there a solution? I don't think so — and maybe there shouldn't be.

Mary's inclusion was a dutiful effort to include a woman in a show that struggles to make room for them, but it isn't surprising that the effort failed. The Watson/Holmes bromance doesn't permit it, and part of me hopes the show will chase the increasing tyranny of this partnership to its grim conclusion. Theirs has become a bad relationship, and it was smart of Gatiss and Moffat to write it that way — even noting that John's sensible façade is masking an adrenaline-junkie damaged by his experiences in the war. Since Arthur Conan Doyle's stories are episodic, not serial, you don't really see the building toxicity of the Watson-Holmes dynamic the way you do in the show — which is far more interested in that relationship than it is in the mysteries themselves.

As for the show's women: Yes, Mrs. Hudson got some great lines in "The Lying Detective." And yes, Euros Holmes may well turn out to be the series' most fearsome villain (I won't believe John is dead until I see it, but that would massively and irreversibly transform the series.) It may be that the Watson-Holmes team is so tight that the only real space available to a woman is on the opposing side. There would be a certain poetic justice in Euros taking Holmes down, but I'm not optimistic that the show will pull that trigger or deliver lasting consequences.

"It's never twins," Sherlock said earlier this season, and maybe it still isn't — it's hard to understand why he didn't recognize his own sibling. And it's hard too, given the show's past decisions, to believe that it will let her own her villainy exist without subordinating it to Moriarty's. But let's hope it is twins this time — for the sake of a great fight, if nothing else.