The only daughter of a March-warden and his wife, Arrwyn grew up wanting to learn how to fight and protect like her father. When she was in her early 20s, she returned from a patrol to find her village had been attacked by White Hand orcs. Her parents survived, but her father was badly injured, and remained crippled after he healed. That event started a deep hatred of orcs, and Arrwyn will do just about anything for the chance to hunt and kill them.

When the orcs' raids began getting more frequent and serious, she volunteered for a small force to go beyond Rohan's borders, to seek help in getting rid of the monsters. Past the Gap of Rohan, the group was attacked by a large force of orcs, and barely got away with half their original numbers. The orcs continued to follow and attack through Dunland and beyond, then unexplainably retreated when they got near the Trollshaws. The few remaining members of Arrwyn's group eventually made it to Breeland, then agreed to go separate ways, each one attempting to gather help for their homeland. Arrwyn chose to stay near Bree-town, and began working with the guards in an attept to gain their trust and cooperation. Not long after, her friend Raedbor, who is practically a brother to her, came to Bree, after being thought lost in the orc attacks on the journey. They are now working together in their efforts to bring home the help Rohan desperately needs.