Of course she was raised that way. Demons were out to take over, and to do that they needed to kill the Charmed One. To kill the Charmed Ones they needed the two of them. They were the ones that could do it, and that didn't sit well with Billie.
Her eyes flicked down to watch Christy's hand as it moved. Her arm twitched for a moment before she forced her hand to stay where it was. She wanted to trust her sister, so she had to let her try.
Did she think Christy was evil? She worked for the wrong side, yes. But because she didn't know any better. "I think you believe you're not working for the evil guys. Because that's all you've known. No, you're not evil, it's just the only thing you know."
But that had to change. She was a witch. Powers weren't evil, they were a blessing. "Powers aren't evil. Your powers aren't evil. We're supposed to use them to make things right."