good question.

Ever heard the saying: "Harboring bitterness is like drinking rat poison and expecting the rat to die?"

I think summed it up best about the "blood" part you wondered about. (BTW, I did too, but scriptwriter Murray Burnett in fact had his "good guy" asking the same thing, then being promised by Dr. Moore that he'd tell him some day if he helped him with his scheme.) Dr. Moore was consumed by bitterness, which happens to so many if not all of us from time to time yet is an equally dangerous occurence for each of us.

So often, when we harbor the bitterness which compels us to seek revenge of some sort all we do is hurt our own life. That happened here, to the extreme. I'd not thought of it 'til he said it, but U_N_T pretty much summarized this plot...Dr. Moore put so much of himself into seeking revenge that when it happened, it deeply and permanently affected not only his adversary (who went through extreme humiliation in breaking off his engagement) but also Dr. Moore himself.