I cannot stand Morrigan, of all the three Origins I've played I asked her to leave the party permanently, she strangely reminds me of Vegeta from the DBZ series, she keeps complaining left and right whenever I feel like helping people that ultimately will in a direct or indirect way help against the cause and the very goal of the game, to fight the Darkspawn, but she's too selfish and obsessed with her "mother"'s laws of survival of the fittest that she completely forgets anything that occurs around her little bubble.
I just couldn't keep her in my party for that reason, and Sten is very close to that as well, and that proves to me how well BioWare made the game and crafted the characters and how good the voice actors are, it's exactly because those characters are so well made that I could "react" to those virtual behaviors just as I would probably done in real life, it's paradoxical to some extent, but it explains why I was so immersed in Dragon Age.