The battle. Billie wouldn't have surrvived it. But it did mean she probably didn't remember the fireball. It was something she didn't have to explain. "I don't remember how it ended or how we surrvived. You know the power we have together, maybe in spite of...everything. Maybe it saved us" said Christy, actually truthfully. "I remember the Triad dying and then Dumain, both of..."
That was not a topic she should really go into with her sister. It wouldn't help either of them any. And that wasn't her purpose for being here. No, she had to convince Billie. Slowly. While making the Charmed Ones suffer.
"It's strange, last time I saw you I was so angry. I wanted to hurt you. I really did but now...I don't know, I...just know you're my sister and I love you and I know what I was doing was all kinds of messed up but I don't know how to be someone better. Will you help me?"