In *The Fellowship of the Ring*, the Orcs of the Misty Mountains are clearly afraid of the Balrog, and who could blame them? But whereas the Balrog killed all the Dwarves he could find after they woke him up, he seems to have left the Orcs alone for the most part. [Other](https://scifi.stackexchange.com/questions/64812/was-durins-bane-a-servant-of-sauron) questions here have established that the Balrog didn't answer to Sauron in any way, so the answer isn't that the Orcs and the Balrog work for Sauron.

Of course, Balrogs and Orcs are both evil, but so what? That doesn't keep Orcs from killing each other left and right. Hitler and Stalin were both evil, but they were intent on killing each other too. 

So why did the Balrog of Moria tolerate the presence of Orcs in his domain? What was the reason for his obvious willingness to tolerate Orcs but not Dwarves?