I'm new to a leadership position, having been recently promoted through a reorg. My deputy manager was too. It's a government position. I didn't choose him, we were both assigned, from different former departments. I think that professionally, he is very competent, clearly ahead of the curve. I also thought that he is a nice guy. Now that I work closer with him, I discovered he exhibits quite rude behaviour to certain co-workers he thinks are not good enough, or do not meet his standards, or their behaviour is not to his liking.
In meetings, he reacts in an annoyed manner to questions he thinks are too easy, dressing down people, constantly telling them that all this is well known, well documented and should be clear at this point in the most annoyed tone. He also speaks in derogatory terms of some of the staff when we have personal conversations. I'm pretty sure he does the same with others.
I don't like this behaviour and I don't like that part of my staff is made uncomfortable. He also accused me at one point during the transition period that I would intentionally shut him out of important decisions. I was able to show him that I didn't, and they were not important anyway. Still, the drama has made a lasting impression on me that he has a short fuse and has to be treated carefully.
So I would like to talk to him: Telling him that his behaviour has to change because I don't want the negative atmosphere in the department I am supposed to lead. I also think it is quite unprofessional. He should lead like a shepherd does his flock, not like an officer his soldiers. That is at least my approach to this. If he won't listen, I think I should show him somehow that in the end, I am the manager and he is just the deputy. Like, enforcing the hierarchy now in the beginning, avoiding constant fights long-term. "Showing him his place".
I am looking for a good strategy to achieve this goal. Or maybe I am wrong and should rather review my approach to leadership?