Malin

Really rather bitchy and arrogant teenage assassin Celeana Sardothien goes with rival assassin Sam Corland to negotiate a deal with the notorious Pirate Lord for their Master, the King of the Assassins. When it turns out that they're not there to collect fines, but rather a shipment of slaves, Celeana and Sam team up to outsmart the Pirate Lord and free the slaves.

Celeana's attitude in this makes her pretty damn unlikable, but she seems to have been raised to be arrogant and stand-offish, so I'm willing to give her the benefit of the doubt.