Why did Rendon Howe betray the Couslands?

He had a lot of history with the Couslands and a massive chip on his shoulder. He also wanted their land.

Can't quite remember the details but the wiki explains some of it.

Nice reasons, but I think, the main reason is: because Rendon Howe's a big, stinking rat.

I told him that I will kill every other Howe. Didn't turn out to be true though Nathaniel is one of my Warden's best friends

Jealousy. How was jealous of Bryce's wealth, power,influence and territory and he also saw the trips to Orlais as a sign that Bryce was selling out Ferelden to Orlais.

Bryce was the ambassador behind Cailan's negotiations with Celene. Given Loghain's reaction to those negotiations, it's not hard to see where Howe was convinced he was doing his patriotic duty to kill the Cousands.

I'm assuming Bryce was an ambassador. There had to be a go-between of some sort to carry those negotiations forward and convice both sides it was a good idea.

Revenge

Along time ago, Howe and Bryce were in the market having ice cream. Bryce finished his first and then decided to take the rest of Howe's ice cream for himself. Howe was furious. He bottled up all that anger for years until he had the opportunity to get his revenge.


He was a punk who wanted what Bryce had.

Basically, it was just lust for power combined with jealousy over the popularity and respect for the Couslands from their peers, the crown, and the common-folk.

Arl Howe's family was also pretty screwed up, as you learn in some of the backstory from Awakening and other materials, he wasn't exactly popular, liked, or respected as Bryce Cousland was. While mostly a bigger deal for a Warden who is a Cousland (like mine), he was basically put into the game to give it an unambiguously bad antagonist. The Archdemon is a bit too alien to really label as a villain, and Loghain is too much of an anti-villain.

Haha! Of course! Everything is the fault of the Cousland family, Maker bless Arl Rendon Howe's memory! Good lord, who exterminated the even least maggots of the treacherous worm, rest in peace on the bosom of Andraste!

I told him that to make him worry for his family before he died. None of my characters were serious about it - if you talk to the noble, who's son was tortured by Howe, he even tells you, that the eldest son had nothing to do with it (which I think was not Nathaniel, but still, if the heir didn't know, what father dearest was doing, it's only reasonable to assume that Nathaniel didn't know too, when you meet him)

I've Never picked that dialogue option myself because it just show to the Arle how much the warden is broken and how effective it was his provocation.He even respond by saying how much he enjoyed killing their mother and laughs even more at them.

Well, again: he doesn't seem to take it seriously.

Because he deserved better? Those final words of his made my noble human warden feel all warm and fuzzy and wishing I could resurrect Howe just for the pleasure of stabbing him again. Had I been able to draw better than deformed stick figures, I would have made a comic strip where my warden expresses my former sentiment and on the next panel Wynn suddenly says, 'I volunteer.' 

Hurray for mage spells. //brick'd