When Strahd was mortal, he was in love with his brother's girlfriend. Her name was Tatyana. On the day that Tatyana and Strahd's brother, Sergei, were to wed, Strahd killed his brother. Distraught, Tatyana ended her own life. Since that time, Tatyana is reborn in slightly different forms. Always, she rejects Strahd's advances.
Most recently, Tatyana was reborn as Ireena.
When the waffle crew traveled to Barovia's past, they convinced Tatyana that she was in danger. Simon killed her with a dart, but Evelyn was able to cast revivify on her.[1]