How to Get The Good Ending
For this ending, you need to side with the Abbott and go after the Governor.
After killing the beast, talk to the Abbott and say you will make the governor pay for his crimes, the Abbott will give you a maul and some keys.
Since you are nearby, go to Brother Jarum in the Abbey gardens, west of the Abbey to get XP, fame and gold.
Go to the village of Thule and equip the Maul of Healing the Abbott gave you.
With the hammer equipped, just walk east until the end of the bridge, the effect should trigger when you can’t go east anymore.
Now go to Eldfell city and confront the governor, you will enter a big fight against dragons. You can fight or run away by using Recall/Town Portal.
Go and talk to Mersant Orasare at the port of Eldfell, the achievement & ending is yours!