The damn things just didn't quit, did they? Spike didn't appreciate being nearly cornered, but he didn't have many opportunities to get away. He'd shot the stupid thing, and it still wouldn't surrender. Wonderful.
Though he was aware of the unpleasant situation between himself and Jayne, firing in the same general direction of each other, he focused on his own fight. There was no time to plan shots. And, for that matter, no time to shoot again. His jaw clenched as the blade made contact, and before he could be certain of the damage he shifted backward, twisting to bring a powerful kick toward the creature's head. Instinct was to blame for the maneuver, as he was so used to disarming and incapacitating normal humans. But then... What else did he have to go by in terms of experience?
So there he was, shifting backward with what little time he'd bought, reduced to harsh, shallow breaths from the combination of pain and blood-loss he'd only furthered with the little stunt. His gaze shifted briefly toward Jayne, attempting to assess just how much damage the other man had taken, before the all-too-familiar weakness settled in. Spike drew a deep breath, releasing it with a pained grimace and what sounded much like a growl as he forced his right arm up to hold pressure against the wound. He wasn't certain how much damage had been done (and certainly didn't underestimate even a weakened reaver anymore), but he didn't like that he could already feel the blood. The moving required to make the kick had made the wound worse than it was in the first place, but it was still a sizable - though not overly deep - cut across his abdomen.
Spike raised his gun again and leveled his aim on the creature's head, the beast within him finally clawing its way to the surface. He took one step back but otherwise stood his ground, smirking as he pulled the trigger and watched to see what happened.