Trust me, I know of demons as well, I am one and my brother is one you don't even want to think about, lol. I'd like to compare notes some day if you'd like.

As for the seal, someone could have tampered with it. If it was a simple seal made for protection, that would easy enough to manipulate and charge with a counter-current. You could set up a charge inside of it, and when the original seal creator goes to check on it, BAM, backlash. It could be a small attack to aggrivate you, or it could be charged with something more dangerous. Blood is powerful, therefore it is equally powerful when used against you, though it is difficult to manipulate a blood ward (I understand what you're saying now when you refer to it as a blood seal; I call them wards).

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VF Mentor and self-proclaimed know-it-all!!!