Princess Serena was not going to let her slave get away with disrespecting her friends. He did not disrespect her but he disrespected her friends and that was not acceptable to her. She had to punish him and she did it as cruelly as she could. She forced the poor guy to be her foot slave and she got him to lick her soles as well as endure her trampling. She even made him eat some food she crushed from the soles of her boots.