[Luvian]

Well it's complicated. But for example if you are a male human noble, you got the support of the nobles, and you didn't kill the Queen's father yourself (Loghain) there is the possibility of wedding her. If you are a female you could have the possibility of ending up with the illegitimate son of the former king depending on how you play your cards. You also have the possibility of playing matchmaker and getting a new husband for the Queen. etc.

As for your Origin. If you take the more evil option and betray your people you won't have a very warm welcome when you come back looking to recruit them in your army. Also for example in the mage origin if you helped your friend get away he will be able to help you in the future when you meet him again on your return.

And as for the recruitable factions. In almost every cases you get to chose between two sides. Sometimes if you are not careful you can also end up with no help from that faction. An example is if you reveal to the mages/templars that you are a blood mage. Both side turns against you.

Also. I haven't finished the game yet but important characters get a prologue and an ending when you complete the game. What happen to them depends on your choices through the game.