Yeaaaaah, Garrus! Your best alien bro...when he isn't in the middle of calibrating something

One thing I especially liked was the various ways you could influence Garrus over the course of the series. He's already a bit of a hothead, but as time goes on you can bring him around to being more by-the-book or encourage his lackadaisical attitude towards rules, eventually making him almost as Renegade as the most Renegade of Shepards. None of the other party members that I can remember allow you to shape their personalities to such a degree.