Received with other companion quests as Hawke begins Act 2.
Go to The Hanged Man and speak with Isabela.
Flirt: Isabela: friendship (+20)
Diplomatic: Isabela: friendship (+10)
Humorous: Isabela: friendship (+15)
(tested on PC, Xbox and PS3 patch 1.04: no approval change for the humorous option.) Using aggressive response results in no approval gain/loss.
The max Friendship you can get is Isabela: friendship (+25) The max Rivalry you can get is Isabela: rivalry (+5). If you chose to flirt with her, you begin a romance with Isabela.