Okay, you might be thinking this is old, but I'm just thinking. Okay, I'm just saying, I think Kiba is jealous of Hinata and Naruto.
Evidence? Okay, Chapter 611, Kiba says to stop trying to act cool in front of Hinata.
During the Imposter Arc, when Naruto and Hinata look at each other, Kiba pulls Naruto's collar and tells him that it is time to go, leaving a smiling Hinata.
Others? I dunno. Please write below and tell me what you think! Thank you! :)