The hissed 'don't' has left his mouth before he's had a chance to think, facing the stranger and standing his ground as if he's prepared to fight. His hand hasn't moved to reach for his sword yet though. Small victories?

The stranger doesn't look overly threatening, or is at least making an effort not to be, so Fenris settles for watching him warily.

"Where are we?" It's a demand, not a question, but it's less violent than his initial response, sounding more like someone lost and frustrated and less like a cornered wild animal ready to lash out.