I've experienced this too. Luckily, I switched roles, so I don't have to engage with him so much anymore, but I still get his aggressive attitude every once in awhile.

He's made woman employees cry. He's randomly shouted at others for thinking they were being "smart". He's also made me and another coworker contemplate quitting on multiple occasions. Dude has two moods: 1. Unreasonably happy. 2. Explosive anger.

When I had to work with him full-time, my mental health was getting absolutely destroyed. Imagine a whole 8 hours of someone indirectly/directly calling you stupid, shouting profanity, and just being super passive aggressive. Oh, and not forgetting the threats of being fired. He made it seem like the CTO was discussing it, but I think it was him trying to get me fired.

I felt like shouting at him the most hurtful words I could think of and quitting every single day.

I've just been working on side projects hoping one of them eventually replaces my salary (trying to find a different job in this economy is really unlikely). I don't want to work with people like this.

"1. Unreasonably happy. 2. Explosive anger."

That was exactly my experience. It was either extremely friendly and fun, or extreme anger. It was terrifying. I would usually stay up 24 hours in a row preparing for meetings because I would be too anxious not knowing what I was going to get.