After a character's STR is lowered, return the Hound to his owner's hand.
This appears to model his fear of fire, but since the wording of the card does not care what the cause of the lowered STR is (i.e. lowered by an effect), one could argue that his return to hand effect applies when a character's STR returns to normal after being raised. Say you have The Hound and the Guard at Riverrun in play, and you just defended a challenge with the Guard. Does The Hound go back to your hand after the Guard's STR returns to normal at the end of the challenge?