My Charlie does that when I ignore him. He will jump up and slap my arm, on the arm of my chair. If I don't react, he will grab my arm, to get my attention. I go through lots of bandaids.

Mattie used to do this, depending who pets her and how. Do you pet with long strokes, head to tail? A vet once told me to pet only a part of the length of the cat, like ears to just past the shoulder. I try to mix up the pets, some long, some short. Mattie seems to enjoy it, in that she no longer bites me and seems to stick around for more petting. It also might help to encourage Cloris to play more so she gets some of her aggressive energy out and not by attacking when you’re petting her. Good luck! It sucks when kitties do this.

I would suppose that those are meant to be "love bites" that have become a little too over zealous. Control is important to small animals when around a huge biped such as us.
Remember a few years ago when a woman lost her arm to her pet lion (or tiger). She didn't want anyone to reprimand the animal because she felt it was just the lion's nature.

I think it ususally has to do with not enough time spent with Mom when they were kittens.

I've learned that a loud sharp cry can work well.

Some do that.