Bevin is a local boy of Redcliffe Village. He is the brother of Kaitlyn and plays a large role in the quest A Missing Child.
Involvement
After The Warden speaks with Kaitlyn in the Redcliffe Chantry, he/she may search for Bevin in Kaitlyn's Home. He is found hiding in a closet on the lower floor.
Result
If you return 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.