Winter Be My Shield — Jo Spurrier

Sierra has a despised and forbidden gift - she raises power from the suffering of others. Enslaved by the king's torturer, Sierra escapes, barely keeping ahead of Rasten, the man sent to hunt her down. then she falls in with dangerous company: the fugitive Prince Cammarian and his crippled foster-brother, Isidro. But Rasten is not the only enemy hunting them in the frozen north and as Sierra's new allies struggle to identify friend from foe, Rasten approaches her with a plan to kill the master they both abhor. Sierra is forced to decide what price she is willing to pay for her freedom and her life...