How to Make a Deal With the Demon in the Fade in "Dragon Age: Origins"by Laurel Storm ; Updated September 22, 2017
During the course of the main quest in "Dragon Age: Origins," you encounter Connor, a boy who is possessed by a desire demon. There are several ways to resolve this situation: one of them involves entering the Fade to speak directly with the demon. Once there, you can either destroy the demon or choose to let it go in exchange for a boon. However, you can only do the latter if your character is a mage and you enter the Fade yourself, since the demon will not negotiate with anybody but you.
Enter the Fade on your mage main character, either through Jowan's ritual or by asking the Circle Tower for help.
Work through the Fade, defeating any enemies you encounter, until you reach the desire demon.
Start a conversation with the demon. Avoid any dialogue options that involve threatening the demon or turning down the deal. Unless your character has the Master Persuasion skill, this includes the option marked with "Intimidate," as that will lead to a second, harder intimidation check that you can only pass if your character has that skill.
Continue through the conversation until the demon offers you a choice of rewards.
Choose the dialogue option corresponding to the reward you want. You can choose between unlocking the blood magic specialization, boosting the approval rating for one of your companions by 20 points, getting a talent point or seeing a kissing scene between your character and the demon.
The blood magic specialization unlock is account-wide and permanent once obtained. If you want, you can save just before the conversation with the demon, unlock the specialization and then reload to get a second reward.