The Preservationists by Jason Daniels

When teenage fraternal twins Daniel and Dustin lose their mother during their senior year of high school, their life journeys split apart. Daniel moves off to a distant city full of romance and history, seeking a new start and finding unusual allies, including his challenging and highly accomplished new boss. He also meets a young viola player, who helps him explore the world around him, and with each new adventure captures another piece of his heart.

Meanwhile, his brother Dustin is lured into drugs and criminality by the town's most seedy individuals and has to be forced back on track by his brother with the help of an intelligent, well-traveled older woman.