My co-worker and our supervisor always seem to be at odds with each other.  When things get really ugly, my co-worker comes to me for help to fix things between them. Since I have a good relationship with both, I have tried to intervene on my co-worker's behalf. But it doesn't seem to help and I'm starting to sense that my intervening is negatively impacting my relationship with our supervisor. When they are at odds, we all suffer. What can I do? 

When you experience the negative effects of the conflict of others, it's natural to want to "fix it" in order to ease your own pain and restore harmony. However, not only is it not your problem to fix, you often get caught in the middle and it's perceived that you're taking sides.

On the other hand, you can't just ignore the problem hoping it will go away. The next time your co-worker comes for help with your supervisor:

Think about how your involvement impacts the situation: You may actually be encouraging your co-worker to continue the conflict by being a ready ear for him. And when you intervene "on his behalf," intentional or not, you have taken sides. You give him and your supervisor the message that you will "fight his battles," setting yourself up to be seen as part of the problem.

Help your co-worker own his stuff: Rather than taking his side, ask him what part he plays in the conflict. If he has difficulty looking in the mirror, give him some kind but honest feedback.

Be cautious about giving advice: Since you primarily hear only your co-worker's side of the story, your advice may harm rather than help.

There may be personnel or performance information affecting the conflict that your supervisor cannot, and co-worker chooses not to share with you. And it's likely your co-worker interprets your advice as confirming his "rightness," and your willingness to take responsibility for solving the problem.

Decline to intervene: Trust your senses — at the very least, your "helpful" intervention is likely viewed by your supervisor as interference or meddling. It's their conflict so let them resolve it.

Deal with your issues: Your concern that the disharmony is impacting your ability to do your job needs to be shared with your supervisor. Be careful to address your concerns about the situation, not your co-worker's.