This characters are part of the story, but they aren't able to be used in battle nor able to support you in one. Most of them only give you quests or are shop owners (some both).
“Warren (ワック Wack) is a boy who stays at Ariela's Tavern. He is sick when Dagran's Mercenaries...Warren
“Kentis is the father of Ariela and Meredith, and also the owner of Ariela's Tavern in Lazulis...Kentis