The Monstrous Duke's Adopted Daughter

Leslie Sperado, a twelve-year-old daughter of a marquess, is treated like a mere instrument to support her beautiful sister. Brainwashed to believe that she deserves nothing but contempt, she suffers an unrelenting torrent of criticism and rejection from her parents. She nonetheless keeps yearning for their love until one day—she is shoved into a pavilion blazing with fire as her sister's scapegoat. After barely surviving the fire, Leslie awakens to her power of black magic and decides to cut ties with her family. Regrettably, she is bound in law to comply with parental authority for six more years. When she learns that her only chance of salvation is to find another guardian, she sets out to strike a deal with the notorious Duchess Salvatore. Will Leslie escape her family's oppression and find solace within her new family?

(Source: Netcomics)