Cats go through this? Wonderful. Six of them at once.
How old are they when it happens, are they actually two years old?
I would say that it depends on how the "attacks" occur. When Kitty first came in to live with us, if either of us were lying under blankets, and we moved under them, usually our feet, she'd get all hyper-alert and pounce on the movement with her claws out. She obviously thought it was some sort of prey under the blankets, and her instinct was to attack. In the first month, there were a couple of times I woke up with sores on my foot, and I was all "wtf??" But then I realized she must have been doing it while I was sleeping, and I either she didn't wake me up, or I went right back to sleep and forgot about it till I saw them the next day.

I just started telling her no, and then I'd take my feet out from under the blankets to show her that my feet are actually attached to me.

It worked - she stopped doing it soon after.
If a cat is biting some part of you that's not under the blankets, I'd say that it's trying to get your attention/wake you.
The thing with cats, they can be fierce, and if they really wanted to hurt you, they easily could. That's why I think in arw's case, it's more of a rough play scenario. The way the cat has bonded with her so closely, it almost makes me think that the cat sees her as a peer, almost like another cat, and this is her way of trying to play. My guys can get quite rough with each other, at times, and yet they're always affectionate toward each other. It's just the way cats roll.
Of course, I could be totally wrong, and there's something else upsetting arw's Lily. I'm just tossing out ideas.
