Hockey has always been a game where players police themselves, when your opponent decides to hit one of your teammates, it is expected that they will not get away with it.
Tonight, the Bruins faced off against the Canadiens, things got heated really early in the game, when the Habs forward Rem Pitlick demolished Patrice Bergeron, Brad Marchand wasn't happy with this play. Take a look at how he responded:
Pitlick's hit was clearly late in the corner, Marchand did the right thing by defending his teammate, especially when you consider how early in the game it was, you do not want to let the Habs set the tone with that hit.
Marchand did a good job defending his team and his captain, Bergeron is usually well-mannered, but this hit must have set him off.