Actually, be cautious of speaking to another employee directly about such concerns. While that may be a traditionally expected and lauded route, in today's HR

Actually, be cautious of speaking to another employee directly about such concerns. While that may be a traditionally expected and lauded route, in today's HR world, it can actually be a no-no. I ran into this once, some years ago. I spoke directly -- and very politely -- with a coworker about a behaviour that was bothering me. The next thing I knew, I was called into a 1:1 meeting and chastised for speaking directly with the employee on the topic instead of going through my management. As long as I am writing, I'll also speak briefly to the topic of dealing with a psychopath. In my limited experience, their world ultimately revolves around them. If a project or activity benefits them (in their perception), you may get along on it and do ok on that specific task/topic. (Although look out, when the exit comes.) Otherwise, where your interests and outcomes diverge, for them their own will always come first. Any apparent involvement to the contrary will reveal itself, sooner or later, to be a facade. It goes beyond just a conscious choice. This is the way they are -- to the core. Once you realize this, it's easier to limit your involvement with them and avoid further entanglements.