So a while back, a buddy and I were on the way to the airport to pick up my Mom from a trip she was on. On the way down there we were having a discussion about our individual gripes about our primary respective fandoms. Eventually I got to talking about this forum and how I was frustrated with some fans inability to see past Tendou "being an ass".
While describing Tendou's character to this friend he stopped me and jokingly told me to stop describing Sheldon Cooper from The Big Bang Theory. And then it clicked a little, I realized that Tendou exhibits a number of symptoms often associated with Aspergers Syndrome. Now am I outright saying "Tendou is an Aspie" and he was intentionally written this way, thusly excusing everything the character does? No.
What I and my buddy are saying is that a mild social disorder along the lines of Aspergers would explain a lot of Tendou's actions. His apparent "lack of empathy", His inability to recognize peoples change in tone (usually when mocking him), Hes pretty much only talking about 2 things (cooking and his grandma), He really only has a couple of strong interests and doesn't really feel much pull to get more, he doesn't seem to really pick up on social cues, and is exceptionally talented.
I'm not saying this is fact or anything but even I was shocked at all the parallels he had picked out in watching only the first 2 episodes. There might possibly be something to that theory.