During the course of the Mass Effect series, only a few crew members accompany you during the entire trilogy. Garrus Vakarian is one of those members. My Shepard and Garrus became allies in Mass Effect and became bros in Mass Effect 3.
You may be asking why this matters; I will share a special moment that occurred between myself and Garrus: During ME3, a scene plays out where Garrus takes you on top of a causeway on the presidium and begins a shooting contest to see who is the better shot. Come the final target, you are given a choice: You can either hit it and one-up Garrus, or you can miss on purpose and boost his confidence.
I have completed ME3 three times, and each time I could not bring myself to hit the final target. Even on my third playthrough when I decided that no matter how strong my feelings for Garrus that I would hit that target so I could see how he would react, I couldn't do it. Missing that shot was worth seeing Garrus so happy in such a dark story.
Watching this scene for the third time, I realized what the game was doing to me. It made me care about a fictional character so much that I couldn't upset him. Before you start calling me crazy, this is not just about my bromance with Garrus; it is also about how BioWare has done something that so many other developers have not: They made the player care about the characters.
This is why video games are the future of storytelling.
With a mixture of great writing and interaction, we players can experience storytelling at a whole new level. We only witnessed a precursser to the character development in the first Mass Effect. It was not until the second game that we saw what BioWare was truly capable of.
Mass Effect 2 was all about collecting the best team in the galaxy, and with that structure, you were able to concentrate on each character. By obtaining their loyalties, you also helped define their personalities.
In Mass Effect 3, however, it is even more personal because of how small your crew is. With fewer crew members, you have the chance to spend more time with each one, and that also gave BioWare a chance to draw out their personalities more. For characters such as Garrus and Tali who were in your crew all three games, the player has the chance to obtain a higher level of friendship with these characters compared to the others.
Whether you disliked the now infamous ending to Mass Effect 3 or not, you have to admit that two stories occurred during the trilogy. First was the overall story arc about the eventual Reaper invasion; second was the story of Shepard and his teammates.
Just after returning to Earth in Mass Effect 3, you are able to have one final chat with all of your allies. And it is in this moment that BioWare was at their best. This was the true ending of the trilogy — a chance to speak one last time with your friends before what is most likely the final mission for the galaxy. It was during these mixed confessionals and farewells that you got to see how the galaxy was shaped by Shepard; you see it through the characters with whom you bonded.
For me, it was Garrus. He was my right-hand man, and he was the one with whom I wanted to charge Harbinger at the end.