Silent Blade

Silent Blade - Ilona Andrews

Mixed feelings about this one. This is set in a futuristic world where some humans are enhanced and those with the enhancements are super-special. Everyone is divided into clans/family where loyalty is a must. Punishment is banishment from said family. This futuristic society is still old-fashioned. Women are inferior and seem to exist purely to make the men's lives better.
Meli is 10 when she gets engaged to 16 year old Celino. She devotes the next years to learning what he likes, his weaknesses (so she can help), etc, etc. He resents his freedom being taken away and breaks the engagement when she is 16. This makes Meli untouchable/marriageable (because Celino might change his mind in the future). So, Meli banishes herself from her family. They use her as an assassin. While she was currently badass, and I liked that, I didn't think the killing in cold blood. Granted, not much was spent on that, so I don't know how many I would consider to be outright murder. I did like how she gave Celino a taste of his own medicine.
Celino isn't a likeable character either, but he does mellow towards the end.
This is definitely a harsh, bitter world where one can infer anything as an insult and seek revenge.