Aversa appears as a manipulative and hostile woman known for her enticing characteristics, while showing a heartfelt devotion to Validar who accommodated her as a young orphan. She also shows rivalry with the Female Avatar and playfulness with the Male Avatar, and also loves to take long baths and swims. Her birthday is November 3.
In Tokyo Mirage Sessions ♯FE, Aversa is the 2nd major boss, encountered in Illusory 106. She is the one that possessed Ayaha Oribe after the Mass Disappearance five years earlier. She cuts her off from the outside world by controlling her ears and her control was only broken by Tsubasa's song. She is encountered as a Pegasus Knight is weak to axe and arrows as well as Electricity and Wind.
Her name is most likely based on the Italian "avversiera" which means female devil.
Aversa's name could also come from the word "aversion", which means a strong dislike or disinclination of someone or something that arouses such feelings.
Her Japanese name, Inverse, means something that is the opposite or reverse of something else.
The Japanese version doesn't explain why Validar brainwashed her. The localization suggests Aversa always had a knack for Dark Magic.
Aversa's outfit as a Dark Flier, both in official art and in character model, is unique; no other character shares the design of her outfit. Her outfit appears to be shorter in game compared to her official art.
Her artwork shows her wielding a Dark Tome, likely Goetia.
An alternate version of her serves as the main antagonist of several DLC chapters in Awakening. She was one of the reasons why some of the Einherjar were fighting Chrom and his army. Notably this Aversa had a relationship with Old Hubba although this was merely a feint in order to get access to the cards of the Einherjar.
Aversa is shown wielding a sword in Chapter 9 while still in her Dark Flier attire. Though Dark Fliers cannot wield swords, one of Aversa's reclassing options, Dark Knight, can.
Aversa is the only non-DLC character in the game that has a weapon named after her; Aversa's Night.
In her B support with the Female Avatar, Aversa reveals that she is eight years older than Chrom. This would make her roughly 27 years old during her first appearance.
If Aversa is reclassed into a class with an outfit that bares her arms or legs, she uses a generic model with light skin, rather than a dark-skinned model. She shares this characteristic with Flavia.
A set of map sprites featuring Aversa in the Mage class line exists within the game data, although they are unused in the main game itself.