it’s be interesting to see how that would play out #hunt down the person who killed sidonis? #learn more why sidonis betrayed garrus and co?
Good questions because the way I approached this situation is a bit different
In my head, the mission plays out normally: Garrus finds out who's responsible for forging a new identity for Sidonis, so he gets Shepard to come and help him meet Fade. Maybe he's in more of a hurry this time, like if they dawdle then it gives Sidonis more time to disappear
So you fight your way to Fade, find Harkin, and Harkin tells you the truth: Sidonis is dead. Garrus tries to figure out why, but even Harkin doesn't know. In fact, you never find out how he died. He's just dead
Actually tbh, maybe nobody killed him. Like I said before, he probably died a mundane death that involved an illness or simply tripping and falling on his head
I think of it as a subversion, because the loyalty mission is already similar to the mission in ME1: Garrus is trying to find a guy that did wrong, but also personally wronged Garrus for getting away from him. He uses whatever resources he has to find him. So in this situation, unlike ME1, where you find him and he dies by your hand, you try to find him, and then find out he's already dead in ME2
You never really know Sidonis' side of the story until you meet him and let him talk about it. The most you know is what Garrus told you. But I think whether Shepard knows or doesn't know about what Sidonis actually did is relevant here. Shepard makes the choice of getting in Garrus' way to delay the shot, which is before Sidonis gives you his side of the story
The point is that it's not solely about "If I kill this guy, things will be better forever," it's also about "I think I am personally responsible for this guy that got away from me, and if I kill this guy personally things will be better forever". Well guess what. The guy's already dead because of something you didn't even know about. So what now? Are things better? Garrus? Hello? Are you there? [Insert entire scene of the aftermath here]