Who do you root for?

So, for the past several weeks, as the NHL playoffs have progressed, I have caught myself becoming a Buffalo Sabres fan. I root for them because of Graham's overwhelming passion for the team. I figure that if they win, Graham will be a happier person. But, when I explained this to my friends at home, they took a totally different approach. They said that you have to root for the opposing teams of your friends, unless you both have a strong passion for the same team. So, according to them, I should have technically been a Hurricanes and Senators fan the last few weeks. It is similar to the way in which they used to torment me by cheering for whatever team was playing the Redskins. So my question is, who do you root for? Although, it is fun to antagonize your good friends, it's also a great feeling for them when their team wins. Personally, I think you have to take it on a case by case basis. For instance, Krauss has shown his love for the Tigers as of late, but this spring you will definitely see me cheering for whatever team the Tigers happen to be facing on any given night. This whole thing is an interesting dilemma that I don't think will ever be solved.