Rotoluncia, from Ultima VII Part Two
In the past, she and Filbercio had been lovers, but they broke apart when his lacking faithfulness became obvious. It stayed that way until one year before the events of Ultima VII Part Two, when Rotoluncia renewed their relationship temporarily. However, she was bitter when he dropped her for Frigidazzi, the blue ice-sorceress.
She therefore concentrated on the topic of Daemons in order to forget this, when Batlin came into town and she thought that the Gargoyle Palos, who was travelling with him, was a Daemon. She became fixed on the idea to control Daemons and when some months later the Avatar came into town, she made the hero an offer of great power, for the price of the secret of controlling Daemons. Of course the Avatar didn't know it, and that made her sour.
So when Filbercio gave a banquet in the Avatar's honor, she attacked the hero in her frustration, but was foiled by the honest Gustacio. Retreating, she took more serious measures and abducted one of the companions in order to force out the secret in the small house in the middle of the nearby lake, her and Filbercio's former "love nest".
That last act ensured her death when the Avatar, brought on the right track by the Mage Lord, found and killed her in battle.