She’ll let you live. Unless you try to steal her gold.

Before their eighth year of life, Sienna and Fawnlum were rivals, but she could not overcome Fawnlum in their sparring matches.
Recognizing that the strongest among their people would fight the strongest enemies, Sienna declared Fawnlum her sister, and where Fawnlum found the greatest battle, there Sienna would be. Like Fawnlum, she’s grown to be about 6 and a half feet tall, and gifted with strength and fighting skill, filling the role of front-line warrior in their four-sister battle-group.
Although highly competitive, she is also very practical, especially in terms of money. As the miser among them, she believes if a person is able, they should do what’s needed, and enjoy the rewards.
Also, a warrior’s riches add to their fame, leading more powerful enemies seek that warrior out. Not that she values gold more highly than life itself, she simply believes in the rewards that come from victory. Therefore she’s right beside Fawnlum, to defend greater and more rugged swaths of Coastal territory from orc armies and other deepway monsters.