QUOTE : The twitch of the hand could mean anything. It could mean that Snape doesn't want to kill Dumbledore. That he flinches at the depth of commitment. That the thought of watching Draco attack Dumbledore and stepping in at the precise moment of failure overwhelms him with tension. But he chooses to leave his hand in Narcissa's. He will never again be the uncertain man who flinched under the gaze of Aurors or Death Eaters. He agrees to kill for Draco, or give his life, or take Draco's place, the way Lily did for Harry.