If you have a look to a social tv chart you can see that tv shows and events generating more engagement among the viewers are the Superbowl, The Oscars, Grammy Awards, The Voice, X-Factor, American Idol, Masterchef The Walking Dead, Game of Thrones, Vampire Diaries.
Analysing them we can see that some are live events, some are talent shows, some scripted series, but all of them have one element in common, they are structured as competitions. Even Game of Thrones, with the fight among Lannister, Baratheon, Stark, or The Walking Dead with the struggle for survival and leadership, or again Vampire Diaries with the vampire-human game are, in a word, competitions.
When there is a battle for a prize, for a victory, for a throne, people decide to choose the one to support. They take its side and they like to tell the others that they are its fans. In sports and talent show this is usual, but in scripted shows actually not. Procedural shows on the other side are generating less buzz because there is no real competition. On the other hand scripted shows with plots based on love relationships (where viewers can take the side of one character involved) can be classified as a competition.
People like to tell who are they for to other people and with social network they have the chance to tell it to the world, standing up for their own ideas and discussing with anyone has a different point of view.
Social tv is all about content strategy (and characters strategy) and when viewers can choose their own “team” they are more interested in engaging with others.