Euphrosynia Heterodyne was a rare female Heterodyne heir, the sister of Bludtharst Heterodyne, and daughter of Clemethious Heterodyne, living approximately 200 years before the start of the action in the comic.
We know next to nothing about her, and the little that we do know comes from a handful of sources:
The Opera Edit
According to the elaborate Storm King opera written by one Portentius Reichenbach, Euphrosynia was the love object of both the villainous Ogglespoon and the heroic Andronicus Valois, and thus part of the "fairy-tale" surrounding the Storm King. Andronicus witnesses her being menaced by Ogglespoon and falls in love with her. A prophecy is announced that peace will only come to Europa when a Heterodyne daughter marries the Storm King. Ogglespoon (re)kidnaps her and traps Andronicus in a bonsai hedge-maze in the process. Andronicus's resulting vow to track her down and rescue her is held as being responsible for the breakup of his .
The Novel Edit
The prologue to Agatha H. and the Clockwork Princess depicts Andronicus about to marry Euphrosynia; she does not appear in person, and everything the viewer learns about her is from Andronicus's viewpoint. She was supposedly assigned to be married to an unnamed Heterodyne ally before catching Andronicus's eye and agreeing to become his wife via a diplomatic courtship, thus ending the war between the Heterodynes and the Storm King. The Muses appear and warn him that she is a cat's-paw to her father, and will betray him. Having no choice at this late stage, Andronicus proceeds with the wedding.
The Jäger Edit
Some more reliable in-strip information comes from a Tweedle and a Jäger named Rerich, who was alive during the actual historical events in question and had some limited contact with Euphrosynia. If he is to be believed, while she "luffed lots ov pipple!" including possibly Andronicus, she was also a typical member of her family, a beautiful "monster" with an appetite towards general chaos and anarchy, and any attempt by Andronicus to "tame" her would have inevitably ended in failure. As in the novel, she is reported to have indeed betrayed him at some point and brought about the end of Andronicus's coalition. Whether they had any children before this betrayal is unknown, but Andronicus evidently produced a lot of children with somebody.between
The Master of Paris Edit
Another Simon Voltaire and a revived Andronicus, adds the tidbit that Euphrosynia, whom they both refer to as Andronicus's bride, some time after having captured Andronicus's devotion, eventually ran afoul of something in master-Spark Van Rijn's laboratory and literally disappeared. What she was doing there in the first place is disputed; Voltaire claims she was snooping on behalf of her family. About the same time it is also that the Jäger Jenka served Euphrosynia in some direct personal capacity, but was not present when she disappeared. When Agatha addresses Andronicus directly a moment before devastatingly weakening him with a weapon blast, (calling out to her with the misspelling or alternate spelling "Euphrosnia"), suggesting Euphrosynia may have had some (possibly vocal) resemblance to Agatha.this one between eyewitnesses
The Baron's Tale Edit
Baron Klaus Wulfenbach to Phil the Storyteller is another possible source of information. It mentions a unnamed "Heterodyne witch" who was the daughter of Clemethious Heterodyne and who put a curse on the Storm King before being destroyed by the Storm King's son. But the true purpose of the story seems to be to allow Klaus to send a message to his own son by means of Phil without Lucrezia-in-Anevka realizing what he is doing and is probably justby