Beware of the snakes that be in the woods. Things you have described experiencing with this coworker fit in with tactics used in this article. I thought about you when I read it this morning. This can happen to people trying to get ahead where they are good workers but get sabatoged by another person that tends to have dark ways of getting what they want.

10 Unbelievable Behaviors Of The Narcissist | Caregivers, Family & Friends