Eyvind:
Muscling your way forward, you lash out with your blade, a confidant blow that goes awry as the rat-thing darts to one side and hisses, baring broad incissors that flick specks of spittle at you. Long, bony barbs suddenly extend all along its back, clearly they were lying flat until a moment ago. The creature gives up the pretense of injury, and turns tail to flee, scampering off into the darkness.
Kneecap:
You can see the rat beastie, which you recognize aas a devil-rat now that its spines are out, wriggle into a crack in the wall and dissappear further down the tunnel.
Gavyn
After a few moments, you beleive that there is in fact nothing comming up behind you.