Bevin is a local boy from Redcliffe Village. He is the brother of Kaitlyn and plays a large role in the quest A Missing Child.
After The Warden speaks with Kaitlyn in the Redcliffe Chantry, they may search for Bevin in Kaitlyn's Home. He is found hiding in a closet on the lower floor.
If the Warden returns the sword (called the Green Blade) at the end of the battle, the Epilogue will mention that Bevin went on to be a great adventurer, often telling of how his sword was used by the Hero of Ferelden to defend Redcliffe.