Phenom is biting the kitten for no reason

I was laying on the couch with Phantom and Phenom was looking at the hummingbirds on the cat tree. She got down and jumped on the couch with me and then randomly bit Phantom on the neck. She has done it a few times before. I am guessing she is showing she is still boss and it doesn't seem to bother Phantom, who just lays there and takes it. Why is Phenom doing this?

like you said, she's just showing her who's boss, it's a dominant behavior, I deal with it too, someone is always clamping down on somebody else around here