Lamar is my favorite GTA supporting character in the series history because his characterization was spot-on. Video games typically have a tough time showing someone with real motivations and actions that aren't motivated by the plot, but Rockstar nailed Lamar from his loyalty for Franklin to his underlying resentment of him. It's quite possible Lamar is the most realistic portrayal of a human being I've personally ever witnessed in a video game (graphics notwithstanding). I honestly can't think of another character - supporting or otherwise - that felt as, or more, real to me.