DH is in a managerial position at work. A few weeks ago he had to make a decision and an employee didn't like it. The employee never said a word about it to DH but instead went to people above DH's head and tried to get him in trouble, resorting to a few outright lies about DH to make his story better. Everybody knows that the employee lied, he has a reputation for stirring up trouble, but it's not a situation where anything can really be done because the accusation is that DH said something rude so it can't be proved or disproved. Upper management has decided to basically tell everyone to get along and wait for it to blow over, which is fine by DH.
The thing is, even though the issue was weeks ago, this employee has continued talking crap about DH, continued to spread this lie and perpetuate the gossip, and ramped up the drama by including a few other managers into the mix. DH had to go talk to their equivalent of HR yesterday because if the employee doesn't knock it off he's going to get himself in trouble and they wanted DH's side of the story. DH has NO interest in pursuing it, he wants to guy to drop it and the whole thing to blow over, but at this point it's out of his hands.
That's all borderline PD as-is, but what pushes it over the edge is that a couple of days ago this employee approached a few of DH's fellow managers and asked how he can get promoted to be a manager, too. Well let's see, you cause the managers problems every chance you get, you go to their boss and try to get them in big trouble over tiny issues every chance you get, none of them trust you (a very important part of the job!), and nobody wants to work with you. So yeah, good luck with that.