Dragon Age Origins Walkthrough Part 41 – Shifting Alliances and Betrayal from Within
These 2 quests are the first of the ones that let you change from Prince Bhelen to Lord Harrowmont and vise versa. They become available after you have completed the first task for either of the potential kings.
Bhelen to Harrowmont, “Shifting Alliances”
After receiving your second task to deal with the Carta head, Jarvia, you want to head over to the Harrowmont Estate. Talk with the Butler to learn the Dulin is in Tapsters. Head into the Commons and visit the Tavern. Dulin is in the back left part of the tavern. He is standing just to the right of the booth in that corner. Talk with him and persuade him that they could use an insider. From there, explain what your present task is and Dulin will see an excellent opportunity shaping up. He tells the Warden that Bhelen hired Casteless Sellswords to kill his brother, Trian Aeducan. Dulin wants you to find the proof of this and bring it back to him.
Proceed along the “Entering Jarvia's Hideout” quest as normal. After you have encountered, and killed, Jarvia head over to the chest in the back of the room, center along the Eastern wall. Open it up to find some good loot and the “Incriminating Documents”. With these in hand, head out of the Carta Hideout and go to the Tapsters Tavern to turn these in to Dulin. He will thank you and accept you into Harrowmont's Service. If you stop by Dulin first you can get credit for for completing the quest on their behalf as well.
Harrowmont to Bhelen, “Betrayed From Within”
Once you have the second task from Lord Marrowmont, head to the Chamber of Assembly to find Vartag. As long as you have not done too much to anger him you will be fine to talk to him and convince him that you are working for Prince Bhelen. This will have him see that you are working for the Prince but doing so in a covert fashion. Vartag will see the advantages of Harrowmont claiming the credit for clearing out Jarvia's carta. He will also see an opportunity to ruin him fiercely. He will ask you to plant some papers in Jarvia's possession once you make it to her inside her Carta.
Proceed along the “Entering Jarvia's Hideout” quest as normal. After you have encountered, and killed, Jarvia you need to find her chest, “Jarvia's Personal Effects”. This is along the back wall of the room where Jarvia came from. You will be given the option to plant the papers inside the chest there. Do so and return to Vartag to claim the credit for completing this quest. If you stop by Dulin first you can get credit for for completing the quest on their behalf as well.