First of all those three series originals comes form different media.
Big bang theory is a TV series. Game of thrones is an adaptation form a famous fantasy novel series that by George R.R. Martin. Attack on titan is a adaption form famous manga series that written and illustrated by Hajime Isayama.
Attack on titan and Game of thrones are adaptations, before animation/TV series comes out .They already have group of audience that loves their original books. Those audience starts discuss on internet. Thanks to social media. This is first waves to spread those TV/animation series information. It become virus topic. Attack on titan become a hot topic on internet at Japan before its animation series release. Same thing happened on Game of thrones. Those two series have their own superiority that from their original book’s fans. Which Big bang theory does not. But there is one good thing for Big bang theory, plots are original, fans are expecting something new and surprise. Those will become a hot discuss topic online as well.
Big bang theory is an American situation comedy that created by Chuck Lorre and Bill Prady. The reason that big bang theory so hot is Sheldon Cooper, one of main character’s conversation. Sheldon is an IQ of 187 genius, he’s so good at professional and lack of daily common sense. This contrast is the biggest hot topic for Big bang theory. It always comes up with some special theory that make people laugh.
Differently, Game of thrones and Attack on titan are different. Those two series are full of suspense and mysterious. They both have giant world environment and mysterious. Game of thrones, fans will focus on fate of different house. Attack on titan focus on fighting giant titan and characters humanity.
Although most of fans might already know most of plot from books, but audience s still loves to watch TV series. Compare with real character or famous scene on their pictures that created in their mind when they reading novels.
Kuso is a big part of virus hot topic spread on the internet.
Such as TV show and culture combine together become a kind of sub-culture.
Those kuso picture not only makes people laugh but also increase audience. People who do not watch Game of thrones but play War of Warcraft might interested in Game of thrones. They might want to know why fans created this picture. Those kuso might increase audience of Game of Thrones. Also kuson pictures might combine different sub-culture in one picture. Different people in different sub-culture junkies will share this picture on internet which will make TV series become virus topic.
One of the main reason that Attack on titan so popular on internet is kuso videos.
It start from gigguk—a famous channel on YouTube.
Gigguk is one of famous animation reviewer on YouTube. This review have 177,791 people watched.
Since his video, people start making joke on Attack on titan’s Opening mv which leads a lot of kuso video released on YouTube.
It bring huge amount of people to watch Attack on titan and start making kuso video as well.
Compare to Game of thrones, Big bang theory.
Attack on titan starts form kuso and spread to worldwide. After people getting interested in this animation. Attack on titan attract audience with its own giant detail description huge mysterious world environment and storyline.