I know this isn't about women or sexual strategy, but it has to do with men and how they act in the current society, and I'm really at a loss here, so please, any advice would be greatly appreciated.

I'm 5'6 and very good at my job. A few years back a tall, handsome guy started picking on me when I started dismissing him for being incompetent. He went all "dark triad and depressed" and would not stop putting me down whenever I raised my head for anything. He used his "status" to fuck with me, essentially. Women laughed, and other beta morons followed him. He made me the clown.

Got him fired almost two years ago though and I busted my ass to improve. Now I'm bigger (muscular), still very good at my job, and the de-facto leader among my peers on professional things.

My problem is this: one of those beta-morons who used to follow him is trying to act the same way he was: he's acting all depressed and "dark", and he also hates the job as much as the other guy. I recently got "promoted" to a new position and I'm working near him, and this idiot is now starting to say that "working with me is hard" and bla bla bla...

He and a few women messed up a couple of projects and the bosses put them on the "black list", but he doesn't even know this, and keeps acting up. Yesterday we were working alone in the office and the moment a third coworker dropped by this guy started complaining about "how he was happy for the first 10 mins that morning until I arrived", and this out of damn blue...

Now I'm done. I'm not keeping my head down for a shit head like this. He isn't joking, he's trying to deflect his fucked up situation on others, and I'm currently the target.

Outside the office I could settle this in a heart beat, but I can't here, and I don't know what to do. If I started bullying him (he's thin, decrepit, weird, a loner, etc), I could get him to cry and back off, but I'd ruin my reputation even more. If I stand still and let him do this, he can keep deflecting his issues on me.

I could wait it out and hope for my bosses to reprimand him for being a depressing moron and making life hard, but I'm not waiting for that. Something's gotta be done.

Any ideas?