Fandom has always seen thematic connections between BBC Sherlock and the Harry Potter stories. Eurus Holmes bears striking similarities to two newcomers to Potterverse: the Obscurial and the Cursed Child. Like the Obscurial from Fantastic Beasts, Eurus can change shape and cause mass destruction, but longs for someone who can soothe her and help contain her powers. Like Delphi from Harry Potter and the Cursed Child, the story of Eurus is an arguably extra-canonical, controversial addition to an established storyline. A look at the connections between Eurus, Obscurials, and Delphi can elucidate what they bring to the fictional universes we already loved.