Board Thread:Lore Discussion/@comment-68.45.229.57-20130720115140/@comment-24327466-20131222221818

Dawnguard has a lot of inconsistencies. If you killed Serana immediately (like a vampire hunter) Harkon would be screwed unless he managed to find Valerica. Of course that assumes that he needs to sacrafice her and not just collect her blood but if that's the case burn the body. You could also kill Gelebor to seal off the bow or collect the bow and put it somewhere inconspicuous, like the bottom of the ocean.