Unseelie duology

Iselia “Seelie” Graygrove looks just like her twin, Isolde...but as an autistic changeling left in the human world by the fae as an infant, she has always known she is different. Seelie's unpredictable magic makes it hard for her to fit in -- and draws her and Isolde into the hunt for a fabled treasure. In a heist gone wrong, the sisters make some unexpected allies and find themselves unraveling a mystery that has its roots in the history of humans...