The death of her father took a heavy toll on Riaphirth. Having been close to him as a pup, training under him, idolizing him, she could no longer stand to exist in the same territory that held so many memories, and no longer had the patience for Arke and her Empire of buffoons. Her relationship with her brother was heavily burdened by their loss, and though she misses him dearly, she also resents him for his choice to stay behind. And so, on one of her scouting missions, Riaphirth fled without him, and without a single glance over her shoulder.
In time she joined the Ardent Ones, who rebelled against Arke. She didn't get along with them well, and they hardly trust her intentions, but she acts as a scout and a spy for them when possible. On occasion she still runs into her brother, but, it's hardly a pleasant reunion.