It sometimes astounds me how well-intentioned Christians describe Jesus. He is almost this timid thing that wouldn't hurt a fly. More like Francis of Assisi than the Jesus described in the gospels.
Early in the book, John describes a scene that should put to rest that Jesus was mild-mannered. He goes into the temple and destroys the money-making schemes and afterwards publicly challenges the religious leaders.
What is also interesting here is what triggers this behavior. Jesus does sometimes behave in a very mild-mannered way. What brings out the anger in him?
I see the common thread in chapter 2 being righteous anger. First he was upset that the wealthy were profiting over the worship of God. Those who came in to offer a sacrifice were essentially told that they had to buy a sacrifice from the temple. Wanting to remain pious, many did it, enriching those who ran the scheme. This exploitation stained the worship of God, so Jesus violently drove them out.
When the religious leaders challenged him on the authority by which he did these things, he declared that he would rebuild "this temple" and raise it up again in three days. Since it took decades to build the temple in the first place, this was quite the claim. Although Jesus meant something different by "this temple", in the minds of the listeners, Jesus was claiming he had authority that the religious leaders did not. (And it's safe to assume Jesus knew this when he said it.)