Vrin plays a fairly brief but crucial role in Agatha's story. It is through her that we learn that The Other , Lucrezia Mongfish. She also reveals some history of the Geisterdamen, but her exposition raises even more questions than it answers. She is the first (and for a long time only) member of the Geisterdamen we meet who communicates in any European language.
She has worked closely with Aaronev Wilhelm Sturmvoraus to both cobble together a (barely functional) copy of the Summoning Engine, as well as sending her sisters out to scour Europa in search of the Holy Child or, failing that, a suitable Sparky replacement to feed into the Engine and bring back The Other.
She is first introduced midway through Volume V, in Sturmhalten, when following Wilhelm's death she is forcibly dragged in as a test subject for Anevka's new voicebox (which, thanks to Tarvek's engineering, was altered to produce a voice which matched Agatha's). Following that, Agatha and Lady Vrin are taken to which also holds Eotain and Shurdlu. It is during this brief incarceration that Vrin identifies her goddess as Lucrezia and confirms Agatha's identity as the Holy Child the Geisterdamen have been searching for all this time. It's also through Vrin that we get an entire sepia-toned page of .
Tarvek sends Tinka to subdue the three Geisterdamen and , but Agatha's helpful little Dingbot Prime, already on a mission from Agatha to open the cell's door, unwittingly frees Lady Vrin and the other two. After Agatha's brief visit with Tarvek, Vrin decapitates Tinka and tricks Agatha into "escaping" in a different direction, a path which lead straight into the Geisterdamen's secret chapel. It's during this walk that Vrin reveals in an off-hand manner that the , which makes that The Other and Lucrezia Mongfish are one and the same. Agatha is then the Summoning Machine, , and The Other's personality .
Lady Vrin survives through most of the Sturmhalten story arc well into Volume VI, very grudgingly working with Tarvek throughout; in their final encounter she nearly kills him with her sword, but is beaten off by Agatha using a combination of the Control Voice and . She is then restrained by the Wulfenbach troops who have arrived on the scene, and she apparently meets her end when her fleeing goddess (the copy once again controlling the body of Agatha) literally gives her an order to "Die!"
Vrin is brought up again much later when in Castle Heterodyne that it was indeed Agatha in control of her own body and not Lucrezia. Tarvek asks her what she "did to Vrin", to which Agatha answers, "Well, I kind of hit her with a broom. I kind of hit her with a broom a lot."
Vrin is just as amoral as her goddess. She never displays any human empathy or a desire to do "good". She shows Anevka's old form, Vrin is even Agatha if she fails to cooperate. (This is an interesting contrast to Eotain and Shurdlu, who are capable of displaying almost-friendly curiosity and happiness.), except in using her body as a vessel for the goddess. And once another copy of the Other is safely housed in
Vrin is first brought before Anevka and Tarvek in her dressing gown, but is later able to dress (out of frame) in her usual attire, which is identical to that of the other Geisterdamen with the exception of a gold necklace and three projections on her headpiece.
Vrin's hair is shorter (and more shaggy) than that of the other Geisterdamen; she cut it herself as a The Other's gateway, which was apparently destroyed by the mysterious Loremistress Milvistle. Vrin could not rebuild it.for failing her goddess. Lady Vrin's task was to protect
Lady Vrin and the Voice
As is true of all of her goddess' lower priestesses and lesser servants, Vrin is subject to control by the Voice.  However, she also displays a greater degree of free will and is mostly (but not completely) resistant to commands from those who are not her goddess (ie. Agatha and Anevka). As Vrin explains, "the mother is not quite the same as the daughter". Once Lucrezia's personality is in control, Vrin seems to discern the difference.
Status as a revenant
Shortly before Vrin's final meeting with the Other and her consequent death throes, slaver wasp-infected by a wasp eater and thus classified as a revenant by the Bug Squad, resulting in her getting chained to a wall. What exactly should be inferred from this fact (in particular, about other Geisterdamen) is a subject of debate.as