This is one aspect of DA2 that I have to say throws me off a bit. (I'm a relative newbie to Dragon Age and I'm on my first playthrough of DA2, currently working my way through Act 3.)
In other Bioware games that I've played (DAO and the ME trilogy), my character's "baseline" motivations are either pretty well established or left for me to sketch out as I see fit. The Warden can have a wide variety of political and philosophical views, but the underlying goal is clear and makes sense for pretty much any way you want to play the character, in that nobody benefits if Ferelden is overrun by the darkspawn. Similarly, Shepard can have a variety of attitudes about Citadel politics, the genophage, conflicts with the batarians, etc., but is always an elite soldier trying to stave off an existential threat to the galaxy.
I sometimes find it hard to understand Hawke, however. She's a refugee fleeing Ferelden and her family is living in poverty at first, and I'm playing her as generally pro-underdog and resentful of authoritarian systems because of how the family has had to hide Bethany for her entire life. But it's still a big step from disapproving of the status quo to repeatedly risking your own life in an attempt to radically change it, and sometimes I feel like there isn't a clear reason for Hawke to do that other than "the game won't progress otherwise."
And is it meant to be seen as morally problematic or illegal when the quests turn violent? I'm not sure. I sometimes bring Aveline along when the quests involve dealing with criminals as opposed to monsters and demons, figuring that it's more like helping with a law enforcement operation in that case, but I did end up skipping a quest when Aveline objected to it and, as a result, never got to recruit Fenris. It feels like I can't really explore everything the game has to offer unless I'm willing to play Hawke as a full-scale vigilante and/or kind of greedy.
It's like Hawke is simultaneously kind of vague as a character - I don't feel like the dialogue choices are really bringing out her attitudes and personality as clearly as with the Warden or Shepard - and a little less controllable, in that some of the important quests just kind of get thrown at you without a clear justification for Hawke's interest or involvement in the first place.