[Warning: Big spoilers from Mass Effect 2 and 3 follow.]
I've never hated another video game character more than Kai Leng.
He is the head assassin of Cerberus, the Illusive Man's most trusted agent. He's focused, intelligent, ruthless and efficient at what he does. There is no regret or sympathy for those he cuts down in his path. Whatever his objective, he will stop at nothing to achieve it.
Kai Leng in and of himself is not an involving character. He has a common enemy profile and is merely set up as a thorn in Shepard's side. It's hard to hate him on his personality alone since he's so cliched.
The reason why I depise him is for what he did to a Drell by the name of Thane Krios.
Thane was one of my most enjoyed characters in Mass Effect 2. His staunch and unwavering determination to separate his moral conscience from his assassinations, to believe his body was merely a tool performing a kill rather than himself choosing to end a life, was intriguing. Even after Shepard debated with him, Thane was unmovable. Yet his constant reliance on prayer after every mission only cemented the cognitive dissonance he appeared to implement.
After every deployment, I woud rush Shepard down to Life Support to see if Thane had anything new to say. I learned much of the Drell and their connection to the jellyfish like Hanar and of his unfortunate past. So when he survived the suicide mission through the Omega-4 relay, I was perhaps more relieved for him than anyone else on my crew. Except Mordin.
The moment I knew I would relish in staining the floor red with Kai's blood was when Cerberus invaded the Citadel, and the Illusive Man's right hand impaled Thane with his sword. While it didn't rupture any major organs, the massive blood loss connected with Thane's Kepral syndrome meant his life was cut short. Even in his last moments, as Shepard and Thane's son Kolyat watched over him, his final words were a prayer for Shepard, to absolve him of the sins of his many kills. Thane was a true friend to my Shepard.
After Kai Leng thwarted Shepard's mission on Thessia, my blood boiled. Never had I felt such tangible wrath for a virtual character before. I knew my time would come. I knew I would snuff out that bastard's life.
Finally I got my chance. Shepard and his team engaged Kai at the Cerberus base. Despite the influx of soldiers that rained down from the ceiling, I focused all my attacks and my team's abilities on the assassin. I cared not for anything else but pounding him into submission, defeated at my feet.
As the battle wound down, Shepard fired one last shotgun blast into his chest. Kai fell.
I was disappointed. I ended him, but there was no closure. There was no chance to inject the poisonous rage he had given to me.
Yet it wasn't over. Shepard piloted the Illusive Man's chair. EDI and Javik looked out at the dying star. But Kai Leng wasn't dead. I watched with still breath as he dragged his bleeding body to his feet. I swallowed hard as he hobbled towards Shepard, his blade in hand, no one reacting to his movements. He stopped behind Shepard and raised the sword. I couldn't help thinking, "would Shepard enter the battle with the Reapers with a disability? Was he about to die?"
Then the flashing Renegade symbol appeared. While my Shepard was almost a perfect Paragon, my unbridled fury at Kai Leng ordered me to push it.
Shepard spun with reflexes that would make a caffeinated cat embarrased, shattering the descending blade with his left fist. In the same fluid movement, he extended his omniblade (a significant moment since my Shepard is a biotic and had never used it before) and thrust it into Kai Leng's chest.
As if Shepard read my mind, he remarked vindictively, "that was for Thane, you son of a bitch."
I can't recall the conversation Shepard had with Admiral Hackett after that mission. I was savouring the moment. After all the time I stewed over what Kai Leng had done to Thane, justice was finally served. My Drell crewmate had been properly avenged.
This is what so many games can't execute. They don't engage the player with the characters in the game. Too often they merely imply a relationship, one that we are expected to slip into as if we had been there the whole time. That doesn't work.
To make someone care about the characters, like any relationship, there has to be time devoted to them. There has to be a gradual building of a friendship, of characters interacting on a personal level. There has to be times where they enter battle or conflict and rely on each other to see another day. We need to speak to them, to learn about them, to find out how they tick. The experiences we have with characters is what forms that bond that makes us care what happens to them.
I've heard much talk about Mass Effect 3's ending and how it wasn't well received, and I was initially concerned. Now, I don't care how it ends at all. No matter how it all concludes, Bioware has done what so very few have managed. I care about Shepard's crew. It matters to me what happens to them, because I feel like I know them. This is the most I've ever invested myself in the lives of people that don't even exist, and that is an amazing accomplishment.
Let the Reapers tear Shepard limb from limb. I killed Kai Leng.