Apart from accepting ridiculous contracts that put Obsidian in a bad position and needing to rush games, he's also always forcing the devs to add stupid stuff to their games. He would also suddenly change the shipping date for games when they still needed work (and threaten to fire people that were working in those games if they didn't ship it by the new shorter date), for example in Pillars of Eternity he decided he wanted to game shipped in March instead of the planned September date, and if not he would fire Josh Sawyer and Adam Brennecke. He would also not pay any attention to what the developers and even other owners would suggest as the best man for the job and overwrite their decisions and pick people that weren't good for the job, etc.
There's also the whole thing with Avowed losing key developers, and it wouldn't surprise me that it's because of Feargus.
Apparently, Josh Sawyer turned in his resignation a few times because of how hard it is to deal with Feargus.
Then there's plenty of other scummery like wanting his two underage sons to be put on Obsidian's payroll when they were too young to work (the other owners blocked this due to being unethical), the sudden cancellation of Avellone's health insurance (he was supposed to have at least one more month but Feargus cancelled it in 2 days), trying to force Avellone's to not work on games or even talk about games he had worked on anymore by using his family health conditions and the health insurance as leverage for him to accept this ridiculous contract, how Feargus is always threatening other owners about if they don't agree or make a fuss about any problems with removing their Obsidian's ownership (and he did do this to Avellone when he raised some concerns with some stuff). Feargus is also too hard to work with and inflexible, which is why most (or all) distributors that worked with Obsidian once would never want to work with them again.
Also when Obsidian was going bankrupt, their employees were working without any payment to try and make the company stay afloat, when the financial situation improved and Obsidian was in the green again, most owners kept silent when it was suggested that they should pay back their employees the wages that they sacrificed in the past, Feargus response was "we never promised we'd pay the employees back".
There's plenty more. Avellone blew the whistle years ago, and Feargus has a lot of dirty laundry and bad history in Obsidian.
Here's an article that talks about Avellone's claims:
https://techraptor.net/gaming/news/...s-about-departure-from-obsidian-entertainment