The Almost Sisters by Joshilyn Jackson

With empathy, grace, humor, and piercing insight, the author of gods in Alabama pens a powerful, emotionally resonant novel of the South that confronts the truth about privilege, family, and the distinctions between perception and reality—-the stories we tell ourselves about our origins and who we really are.
Superheroes have always been Leia Birch Briggs' weakness. One tequila-soaked night at a comics convention, the usually level-headed graphic novelist is swept off her barstool by a handsome and anonymous Batman.
It turns out the caped crusader has left her with more than just a nice, fuzzy memory. She's having a baby boy—an unexpected but not unhappy development in the thirty-eight year-old's life. But before Leia can break the news of her impending single-motherhood (including the fact that her baby is biracial) to her conventional, Southern family, her step-sister Rachel's marriage implodes. Worse, she learns her beloved...