Dark haired and dark eyed, Catherine was a short lived blazing star in the firmnament of the royal family of Amber. She had a fiery temper and an impulsive nature like that of her elder sister Eowyn, which led her to her early grave.
The defining moment was probably her loud screaming match with her father after Eowyn's death in 624. Catherine was only 12, but she was outraged that Gendo made no effort to ride forth and bloodily avenge Eowyn's death. Gendo was too busy trying to avoid Amber being crushed entirely to engage in such a specific quest for vengeance, but it's hard to successfully convey that to an angry twelve year old. After being dressed down in public by him as a result of this (the screaming match had been at a major public dinner), Catherine tried to prepare herself to get the revenge herself. Prince Saionji, though he tried to restrain her from running off as early as she did, tried to help her prepare to be ready for the day when she could get her revenge.
In 627, she deemed herself ready, and slipped out of Castle Amber, gathering a war party of similarly impetuous young Haradian nobles, and tried to raid the Cimbri to avenge Eowyn's death. She was defeated, captured, raped, and killed by Arovisticus, one of the major Cimbri war leaders.
Catherine's death led Haruka to step up Juri, Corrine, and Haruka Minor's combat training, and to do her best to keep them away from the war until she felt sure they were both ready for battle and sensible enough not to do anything suicidal.
There is some reason to believe that Haruka's five children, if they had all lived to maturity, might have become the Children of the Elements of that era, with Catherine as the Child of Fire, but this did not come to pass.
Catherine of Pariseau, Regent of Ember, bears a strong physical resemblence to how Catherine of Harad would have appeared in adulthood. (Except that Catherine of Harad was much paler in complexion).