Isabela

Background
Isabela is the captain of a pirate ship named The Siren's Call. Zevran, if he is in the party, announces to the warden she is know as "Queen of the Eastern Seas" and "The Sharpest Blade in Ferelden". She resides at The Pearl in Denerim to let her men fill up on supplies and other "pleasures from dry land". She is originally from Rivain, but she has traveled far and visited many places during her life.

She has picked up a special fighting technique during her travels, one that depends on speed instead of strength. Since she has learned this technique by dueling many different warriors, she calls herself a duelist.

Involvement
Isabela is able to teach the Duelist specialization to the party. To convince her to do so, there are two options: Beat her in a game of cards, or "get to know each other better" by following her to bed.

To beat her in a card game, The Warden will have to be dexterous enough to catch her cheating or subtle enough to cheat. To get the option to get to know her better, The Warden will have to be persuasive. If Zevran, Alistair, or Leliana is in the party, they can also "help" The Warden win against her, but will only offer their assistance if they currently romantically involved with The Warden.

Trivia
If you have Zevran in your party, he will be invited to join you if you chose to follow Isabela to bed in order to unlock the Duelist specialization. Zevran's approval rating will also increase by this. Leliana and Alistair can also join you with Isabela if their personality is hardened, even if you haven't slept with them yet. If the Warden is a woman, Leliana's approval will increase.

If you are in a relationship with Zevran and have hardened Leliana's personality and are in a romance with her, you have the option of a foursome. Unlike other lusty or romantic situations with people, this one does not appear to have any specific cutscenes or sounds, only the conversation in the Pearl before and after.

If you are female but not in a relationship with Alistair, he will wonder if he's dreaming, and then tell you he's going to jump in the ocean.

Morrigan is not nearly as open-minded about Isabela as the other romanceable companions. She will strongly disapprove if you bed Isabela and tell you to rinse off the stench after you are done "rolling around in the gutter".