strive wrote...
I do the opposite of you. Miranda is presented as professional, cold, pragmatic, etc. outside of Samara I would say she is the most prepared on the squad to take anyone's life and deal with the fallout emotionally.
Stepping into stop Miranda isn't worth the risk of collateral damage imo. I don't think Niket deserves to die, but he isn't worth risking Enyala who is a trigger happy merc with her gun pointed right at you, and is hellbent on getting paid for get Oriana to Mr. Lawson shooting at you. Maybe Niket is captured by Mr. Lawson and is tortured for information? Niket is pretty much dead once he involved himself. Is it gonna hurt Miranda you betcha, however she was already wounded, and Niket was already basically dead to her.
Garrus on the other hand has been putting unreasonable expectations on himself. He thinks vengeance will make his failure as a leader hurt not as much for him or his men's families. However the point is Garrus didn't fail, and if you let him shoot Sidonis that to me reinforces that he did. Garrus needs to open his eyes that he isn't at fault and seeking out Sidonis on motives of unbridled wrath or "justice" for his false failings isn't a healthy mindset.
Just my two cents on those two situations.
Normally yes she is (or can be) one of the coldest people just before a kill. But this isn't a normal situation, she's personally involved. About as personal as she gets. Recall her reaction if the merc kills Niket (I know you never see it but you know what I'm talking about). That kind of outburst is definitely NOT Miranda's "business as usual". If she were her normal detached self, she would recognize that a loose end has tied itself off and what's more, the merc is distracted, the perfect opportunity to strike. Strike she does, but in anger, and not as a proffesional.
The way Shepard stops her could've been better, granted. But stopping her was the right decision if Shepard cares about her psychological well being.
I don't agree with your interpretation of Garrus' motivations. It's not about him feeling better (and his feelings of guilt are not unjustified, even if he couldn't have prevented his team's death), it's about evening the score, exacting retribution, an eye for an eye. Really, I think he's pursuing Sidonis much as Samara might. The only difference is he is personally involved, since it was his team that died. Also he hasn't had centuries of experience learning to detach himself.