The Dwarf Origin story is not a bright one. As a casteless Dwarf you'll have a hard road ahead of you. This guide will help guide you through the origin story of the Dwarf Commoner.
From Rags to...
If anything, the title of your lot in life - that of a supposed Dwarf Commoner - is deceiving. As you discover quickly in the Dwarf Commoner origin story, you lot in life is the lowest of the low. You are a Dwarf without a caste, which in Dwarven culture makes you scum.
The beginning of the Dwarf Commoner origin story involves a long conversation between yourself, your sister Rica, and a thug named Beraht. This initial conversation largely exists to give backstory, so despite his ruthless nature Beraht takes it easy on you if you give him lip. After your conversation with Beraht, you should talk to your sister, Rica, and to your mother, Kalah, both of whom can give you more backstory.
When you exit into Dust Town you will meet a Dwarf named Leske, a buddy of the player character. In addition to some friendly conversation, Leske will give you all the details about your mission from Beraht. You are to find a smuggler who Beraht thinks is taking a cut and deal with him.
There are a few Dwarves you can speak to before heading off to complete your new quest, so feel free to explore the areas you can gain access to. There is not anything special, but the conversations help flesh out the story, so I suggest taking the time to poke around.
Once you're ready, head to the tavern to find the smuggler, whose name is Oskias. Speak to the tavern owner and he'll point out Oskias for you once he realizes you're Beraht's thugs and not the typical low-life.
The smuggler will also become very skittish once he realize that you're there to talk to him about his activities. You can either kill him, which earlier conversations indicate is preferable to Beraht, or you can let him go. You'll get the goods you need to bring back to Beraht either way, and no one will try to stop you.
Once you're dealt with the smuggler you'll need to go tell Beraht of what happened. He will give you a hard time if you didn't kill Oskias but won't harm you. In either case he'll tell you that he has a new mission for you and Leske. Beraht has bet a lot of money that a certain fighter will win a fight at an event called The Proving and he wants to make sure the right fighter wins.
Head to The Proving and get by the guard by providing him with the pass Beraht gave you. There are a few people to speak to along the way, and you can meet Gray Warden Duncan for the first time. Whenever you're ready, head down to the fighter's barracks. You'll find that the fighter Beraht has put his bets on is passed out drunk.
You have only one option - dawn the fighter's gear and enter The Proving in his place. He has full plate armor, so no one will be able to notice. Your only other task before heading into the Proving is to speak to another fighter named Mainar. This will allow Leske to drug Mainar's drink, giving you an advantage.
The Proving is quite simple. You only control you own character, and the fighters are fairly easy, but if you're having trouble remember to use the stuns and knockdowns you've learned. There are three fights in total, which you will engage in one after the other. After the third fight you'll be declared the winner.
But of course things aren't going to be that easy. Without warning the drunken fighter you're fighting in place of enters the arena. Suddenly wise to your deception, the guards cart you off to jail.
When you wake up you find that you're not in a normal jail. Beraht wants to deal with you personally and has had you transferred to his own private cells. A character named Jarvia, who you've encountered with Beraht earlier, will explain to you how painfully you're going to die and then leave.
You'll have two choices for getting out of the cell. One is to search the cell and find some wooden picks which will allow you to escape when the guards aren't looking. The other is to talk to a nearby guard and kill him by cracking his head against the bars of the cell and then taking his key. Either way you'll be free, and you'll want to visit the chest in the room which holds your belongings.
Once you're out, you'll have to escape from Beraht's lair. This is basically a long dungeon crawl in which you'll fight numerous thugs throughout a series of rooms. Your opponents are not well equipped, but be sure to search their bodies for loot and for health potions, which are your only method of healing in combat for the time being.
As you might expect, the end of the dungeon results in a confrontation with Beraht and two more thugs. This fight is more difficult then the previous ones. Be sure to take down the two easier thugs first and then deal with Beraht. Remember your health potions, as you'll likely have to use one or two.
Once you've slain Beraht, loot everything and leave.
First Steps Towards the Surface
Finally, you've escaped Beraht's clutches. But you don't get far. Guards are waiting outside and are surprisingly unhappy that you've just killed the ringleader of a notorious gang. Luckily, Duncan of the Gray Wardens is also at the scene. He was impressed by your performance in the Proving and is ready to draft you into the Gray Wardens.
There are many ways to have this conversation, but the results are the same. You'll be drafted into the Gray Wardens. Leske is left behind, as is your sister, although neither are too troubled by the idea. Try not to worry about them for now, as it will be a long time before you'll be coming back.