As far as I can determine, cards use "its controller" when they're talking about the controller of some other object. "You" is defined:
109.5. The words "you" and "your" on an object refer to the object's controller, its would-be controller (if a player is attempting to play, cast, or activate it), or its owner (if it has no controller). For a static ability, this is the current controller of the object it's on. For an activated ability, this is the player who activated the ability. For a triggered ability, this is the controller of the object when the ability triggered, unless it's a delayed triggered ability. To determine the controller of a delayed triggered ability, see rules 603.7d–f.
A card such as sleeper agent deals the 2 points of damage to its controller, but the text says "you".