There's no easy way to explain the absurdity and paradoxical nature that is despising a fictional television show character. On one hand, they are simply a written component of material crafted into a story meant for entertainment. However, unless you've experienced hating on a television show character before, you'll never understand the complete validity of a character ruining a television series for you.
You and I know this feeling. It happens whenever a certain character shows up in a crucial scene, wrecks several fictional situations in the season's duration or just acts in a way that makes your blood boil. Once that begins, the agony of wanting them dead remains until the series finale is over with or they really do get booted off the show. You know it's all for television, but you get so wrapped up in the lives and stories of the characters that it can be hard to separate falsity from reality. It's almost as if you live vicariously through the characters after a season or two reels you in.
For me, this immensely frustrating character is Dr. Tara Knowles from the hit FX television show, "Sons of Anarchy". Tara, in my eyes, is an annoying, pathetic and massive contradiction. She's a surgeon with no social common sense or awareness; a crazy cat fighter and a spineless weakling at the same time. She pushes the envelope at all the wrong times and pushes my buttons at all the crucial ones. These are just some of the many gripes I have regarding her character in the popular television series. I don't think I'm naïve to think many people have a Tara they hate on in their favorite television show.
Whether it's their personality in relation to your own, their decision-making processes in comparison with yours or the mounting chaos of their just being there, you can't deny you become a different person when reacting to the actions of this character. You become more passionate when either loving or hating characters. I think when you feel strongly about a character one way or the other it shows one of two things. The first is that the writing for this character and their backstory, personality and choices were done thoroughly and were well crafted (or it would not have upset you/overjoyed you). The second is that the person set to portrayed this character (i.e. the actor or actress) represented the true essence of the written character and brought it to life with their talented acting abilities. In most cases, both reasons for either adoring or despising a character are shown. Writing is a powerful tool, but so is the acting for bringing the written character to life. Even though there's some silliness to hating a fictional character in a television show, you see and get to experience the great thought process that went into making the character you hate who they are.