It's complicated to explain to someone who isn't a telepath, [Because there's really just no good way to communicate things that Nathan won't have a point of reference for - how do you explain the color blue to a person who's been blind all their life?] But basically it's not exactly difficult to see the presence of an outside influence if you know what you're looking for. It just... feels wrong, and you can sort of tell how it's situated itself and carefully peel it off.

Some suggestion's more difficult to work through than others, but as long as there's no actual damage done, it's not hard to untangle things. [At least, it's never really been hard for him.]