Recently started my vamp hunter playthrough, and I found out that if you speak to Serana after rejecting Harkon's "gift" but before he banishes you (there's literally about a 5 second window to do this), she will say something to the effect of "it's probably best if we aren't seen together right now." Thing is, I can't really think of any reason for Beth to put this in, since there's only a few seconds in which you can her her say it, and the next encounter that you have with Serana is one quest later, when she goes to Fort Dawnguard to find you. Any thoughts?