The prose in Cyn Vargas’s debut collection, On the Way, has a casual, unforced power. Whether suffering through a parent’s disappearance in Guatemala or a vicious haircut on Division Avenue, her characters speak to the reader with an appealing frankness, confessing the most difficult aspects of their histories with a welcome, ironic sense of humor. “The kids were used to me not having any new clothes, or new Trapper Keepers, or those fancy juice boxes that weren’t really boxes at all,” explains the narrator of “Then It’s Over.” “They almost expected me to get a bad haircut, too.”