In “Porcupine,”—from her new collection Baby in a Box—as in all of Sarah Braunstein’s writing, there’s a lifetime of wisdom distilled and compressed into her firecracker sentences. Susannah, the story’s narrator, is adrift. Forty-two, finalizing a divorce, she’s living “for that month” in a sublet in New York. Into her life comes Edgar, twenty-five, a couch surfer wearing aubergine Brooks Brothers pants, in whom she sees both a chance for escape and the possibility of stability. If those seem incompatible, well, it’s an appropriate starting point for this particular story. {read}