For background, I own and manage a large scale gaming community (Minecraft) where we are a registered company, though the company registration part doesn't matter too much. One of our employees who I agreed to give 25% royalty to a gamemode he develops frequently makes malicious remarks whenever we are having casual conversation, and would make them in a jokingly manner.
Let's call this person Jeff. Jeff would sometimes make joking remarks about wanting to leave backdoors in other companies he's actively working for, or talk about how far he'd go to ruin someone's personal life if they were to ever screw him over etc.
I'm not exactly sure why he's making these remarks directly to me, especially given I am his employer. However, because we are friends I pretend to laugh along with his remarks. From a business perspective, something like this is seriously concerning and given the kind of malicious remarks he's making, and makes me wonder if he contemplates doing the same thing to us. Jeff tells me he is only joking when he makes these remarks, however it indeed uncovers what kind of person he may be.
Removing this individual is easier said than done, due to the whole royalty and licensing agreement. There could potentially be other serious events that unfold, such as backdoors I have mentioned. I should note this person considers me a close friend, but I cannot see how that is the case when the code we are running on also has backdoors which he claims serves as protection incase I were to "screw him over" etc.