[quote=shya100;69916476]I don't think you can ever regret not killing someone, surely that goes against human instinct. It is in our make up to rationalise away things like that.
Yes, (It's the killing 1 to save X argument isn't it?) but Quinn was introduced as Dar Adal's main man, a black ops agent, who a few episodes before was two seconds away from killing Brody until Estes called a halt. I think the 'spoilers' in the previous posts are correct as to the reasons why
I just found it odd earlier in the season (and assuming Quinn believes Brody is responsible) that the losses in the bombing and possibly his own culpability in it by his failure to follow orders hadn't been covered. Then again he's a secondary character to Carrie, Saul and Dana

so maybe it's just been glossed over. It's reasonable to say a build up of all these things are now taking their toll on Quinn and I think it's a good storyline to show the psychological toil.
Has Quinn spoken about Brody this season?
Also, from S2, I can't remember whether Saul knows Estes tasked Quinn to kill Brody, or just that Estes was going to have him killed?