Complex sentence: Stavers could turn on the charm to the "faves" when she wanted to, but she was also known to threaten some of them, too, if she didn't get what she wanted from them.
Split into simpler sentences: Stavers could turn on the charm to the "faves" when she wanted to. However, Stavers was also known to threaten some of the "faves", too, if she didn't get what she wanted from them.