Yeah, monkeys can be pretty mean. My aunt and uncle had a spider monkey that weirded me out. It would sit there in it's cage and stare at me. Then it would throw grapes and stuff at me and then just stare at me some more. As much as it disliked me it really hated the family cat.
When it would escape it's cage it would tear through the house chasing the cat who was terrified of it. And this was no small cat. It had an attitude and normally wouldn't take shit from anyone. But when that monkey was on it's ass it would make these loud terrified cat noises and run for it's life while that monkey was chasing right behind him. They would tear from room to room knocking stuff over as they went until my uncle would yell at them. Then the monkey would head for the top of the bookcase and grab knick knacks to throw at anyone that approached him except for my uncle.
Thank God the thing finally died. I'm sure he went straight to monkey hell.