Possible Clues:

• Fair game in more senses than one, relatively speaking?
• Target for criticism etc.
• Target of abuse, relative's friend
• Target a friend of the family?
• Relative's friend is an easy target for criticism
• Do not begin to tease and attack scapegoat
• Soldier's colleague picked up easy target
• Taking time off at first, kids join friend for game
• Fairground game — target for insults
• Your shy relative is fair game