I agree upon Arl Howe. I don't think Lohgain even liked to deal with him, only to justify his existence for political strategy only rather than an agreement as to his means. At least with Lohgain, you could say he did it out of nationalism and deep consideration of Ferelda. Arl was just a vicious bastard through and through --- and may I add -- a very weak one once you confront him.
Howe was a big pile of resentment: his father was hanged by the Couslands for being an Orlesian collaborateur, despite having had no choice in the matter (his lands were the first to be invaded by Orlais and any hint of defiance toward the occupier would have brought the undiluted wrath of the empire over his kith & kin), Rendon then spent over three decades keeping his pain and understandable resentment to himself in order to keep his tenuous rank as a "honorable" lord, ended up in a loveless marriage so he could rebuild his family, and that's not even counting the fact that he probably suffered from brain damages at the disastrous battle of white river.
Of course, most if not all the pitiable aspects of his personality become known to the player only post-mortem in Awakening, so it's hard to forget 80 hours or so during which he was the biggest jerk in town.
As for Loghain, he was not that "patriotic": he clearly hated Orlais more than he loved Ferelden, choosing to put the very survival of his compatriots in jeopardy rather than accept much needed help from Orlais, tried to bully the Banns (who are not mere barons but elected officials) into submission instead of taking their demands in consideration, and while Cailen's bravado was mostly a show to keep morals up, Loghain showed that he had become utterly enamored to his own legend, assuming that everyone would follow him because he was "The Hero of River Dain" and that any dissent could only be treasonous, going as far as imagining that his headstrong daughter had been brainwashed by the Grey Wardens when she turned against him: his deeds were a lot more irrational and driven by personal resentment that they appeared at first glance.
***
It might be more accurate to say it was Deus doing all of the work since it created Miang and Cain, but they both seem to have fairly high levels of autonomy themselves
Miang is an interesting case, as she simultaneously is self aware and denied free will: she's an intelligent cog in self-perpetuating machine: she's not coerced into playing this role, Deus is, after all, little more than a broken mindless automaton driven solely by survival instinct, it's just that her programming renders her utterly incapable of even thinking about escaping her designated role: talk about a nightmarish fate...
Not that it gave me any regret when Fei used his Xenogears to tear her apart limb by limb, mind you.
***
So, seeing how vassal races build AIs that turn against their masters, the Leviathans solve this by building an AI, that then turns against them.
One questions how a species so unbelievably idiotic conquered the galaxy.
Look at the eventual downfall of every decadent ruling class in every human civilization recorded in history: heirs and descendant of gifted war lords and political leaders who convinced themselves that their blood carried their ancestors' skills and talent, came to see themselves as inherently better as the commoners they lorded over, and concluded that the painful lessons of history did not apply to them because they were oh so much better at everything than everyone else.
The Leviathans are the same, only on a much bigger scale