She couldn't see it. His gaze focused on Dawn again, lying there...and now he noticed the bite marks. That hint of blood. Fury shot through him, anger and rage combined and fueling it. A snarl bubbled up from his chest, and Spike punched at the ground (leaving a small divot). Then he was on his feet, stomping a bit away from Diana.

"YOU SODDING FAIRIES!" Spike yelled, emotion heavy in his voice. "QUIT IT WITH THE BLOODY VISIONS ALREADY! OR I'LL MAKE YOU REGRET IT! I'LL TEAR YOUR SPINES OUT AND MAKE YOU PLAY 'EM LIKE A XYLOPHONE! I'LL TIE YOU UP WITH YOUR OWN GUTS AND TREAT YOU LIKE ONE OF THEM PAPER-HORSE THINGS YOU BEAT WITH A STICK. SEE WHAT COMES OUT!"

Please don't mind that he's having a bit of a tantrum, yelling at the sky and venting that fury. If he could kick something or throw something he would.