Moriarty underestimating Joan, to whom she referred as Sherlock’s “mascot,” is what leads to her undoing. Sherlock and Watson, in effect, turn their weaknesses into strengths: for Holmes, it’s his addiction; for Watson, it’s her novice status. In “The Woman,” Watson feared she wasn’t ready to handle investigations without Sherlock, though he’s quick to assure her that she’s simply underestimating her own abilities. In “Heroine,” Watson is every bit Sherlock’s equal, though Moriarty lacks Sherlock’s ability to see it. Ultimately, it’s Watson who serves as the true catalyst for Moriarty’s downfall, which is fitting, since Joan is the true human connection Holmes has made, not “Irene Adler.” This is solidified in the episode’s conclusion, as Sherlock names a rare species of bee after Watson: Newglassia Watsonia, the product of a bee thought incapable of pairing with other species. Not unlike Holmes, who initially resisted Watson’s partnership, yet now couldn’t possibly be without it. It’s a metaphor for their relationship that’s equal parts overt and beautiful.