Serena is totally, completely shocked, because... What do you say to that? No fault, no responsibility. Things just happened. And yeah, this time -- like last year -- somebody shadowy from the past is trying to draw her back across the line, so it is a little more coincidental than she should ignore. Like even for Serena the timing should be ringing some kind of bell that somebody has it out for her. On the other hand: fuck that, because she wasn't doing anything except trying to be as nice as possible to a boy who never deserved it, over and over and over, and getting shit on just as hard when there were literally no problems at all as when the freaky occurrences were piling up. She's not in charge of the world or the people in it. That's Dan's job.
Here's a little story. About four months ago, give or take a week, two sisters were standing on a street corner in Brooklyn. They were closer than close, once, until one night when things broke. One of them locked herself up tight, and ignored the fever; the other one just let the fever burn. And Serena's little brother got hurt, in one of the worst ways you can be hurt at that age. And Serena accused the other girl of doing it on purpose, just to hurt their family. The other girl's name was Georgina Sparks. And she promised she would never hurt Eric.
"You know, you used to tell me that you were afraid that people couldn't see the real you. Well, maybe you're the one who can't see yourself. From where I'm standing, this is who you are."
That's how far down it goes, is what she meant. She was asking if Serena could believe there were things she wouldn't do, lines she wouldn't cross. Because she wasn't sure; she needed to know. She needed to know she could stitch herself back together. She just needed Serena to make her feel better.