Sea Change by S. M. Wheeler

Lilly Rosa hasn't had the easiest childhood. Her parents, though wealthy, are always fighting and her gender and disfiguring birthmark have disqualified her for either heirdom or advantageous marriage. Her secret friendship with a loquacious kraken named Octavius has given her all the joy she needs, until he is captured and she needs to buy his freedom. And his freedom comes very dear. 
At this point the fairytale turns dark. 

With beautiful prose and a strong hand for character building, Wheeler spins a tale full of blood, friendship, and extremely difficult choices. I was powerfully reminded of the Hayao Miyazaki's film "Princess Mononoke" and Guillermo del Toro's "Pan's Labyrinth", in that while Lilly solves her problems it's not without change and gruesome loss.