As far as most folks who know you are concerned, you’re a perpetual knife in someone else’s back. That rep might not be accurate (see the Flaws: Cultural Other, Infamy, Troublemaker, and Profiled Appearance), but people expect treachery from you even if they’re wrong to think so. Subtract one die from any non-magickal dice pool you employ when you’re trying to get other characters to trust you. This penalty does not extend to Arete dice pools when you’re casting Mind-Sphere magick (or any other Sphere’s magick, for that matter), but if you’re having to cast spells in order to be believed, then you’ve kinda just lived up to that reputation.