Captain Scarlett

Captain Scarlett is the main NPC that the player interacts with during the course of Captain Scarlett and Her Pirate's Booty, the first DLC for Borderlands 2. She, like the Vault Hunters, seeks the treasure and already knows where to find 2 of the 4 pieces of the compass needed to locate the treasure. Being a pirate she is extremely untrusworthy and attempts to betray the Vault Hunters, as she had promised.

History
After hearing about Captain Blade's treasure, Scarlett and her friend Sandman mutinized a ship out in Wurmwater. Sandman and her then found two out of four pieces for a compass that would lead them to the treasure. Scarlett then betrayed Sandman by trying to kill him to get his compass piece, he got away with his life and then started a gang to take down Scarlett. During her quest to get the treasure, she recruited Hermit, who she then kicked out due to how he was stalking her. Scarlett then finds a Rakk Hive and keeps it as a pet named Roscoe, who then gets eaten by the Leviathan, a massive creature that guards the treasure. An unknown amount of time later, Scarlett meets the Vault Hunter and asks if they could help her find the treasure. Throughout their journeys, Scarlett says several times that she will betray the Vault Hunter to get the treasure. After recovering all four pieces of the compass, Scarlett sends the Vault Hunter to Magny's Lighthouse to see where the compass will lead. Scarlett then sends her crew to kill the Vault Hunter, finally betraying them. When the Vault Hunter follows Scarlett, they both get eaten by The Leviathan. The Vault Hunter catches up with Scarlett, who has reunited with Roscoe, after The Vault Hunter kills Roscoe, Scarlett runs away saying to the Vault Hunter they'll meet again soon.