Bevin is Kaitlyn's little brother who has gone missing.
He can be found in Kaitlyn's Home and if questioned, Bevin will admit that he ran away from the chantry and returned to his house to in order to retrieve his grandfather's sword, The Green Blade. His grandfather was a famous dragon hunter, and Bevin feels that if his father were still alive, he would have used the Green Blade to defend the village. Bevin wished to use the sword to defend the village too, but upon returning home, he realized that blade was still too large for him. He can be persuaded to give the Warden a key in order to retrieve the sword.
If you return the sword 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.