Old version under the cut!
(I really like the idea of a story where a shinigami takes on the image of who you could become if you use the Death Note. Light kills his first person and Kira appears. He can decide whether to become this hateful person he sees in front of him, or manipulate and lie to him until he can become something even better - en even more divine god.)
((Oh, and I really love BB. BB is the person L could have become, had he taken a few wrong turns.))