In 'Mud', Matthew McConaughey's Mud has a sad story. Mud grew up in a tough environment which influenced his actions and relationships. He made some bad choices in his youth that have followed him. His relationship with the two boys in the movie also has a tinge of sadness. He's using them in a way to help him get to his love, but at the same time, he forms a bond with them. And his overall situation of being hunted and his desperate love for his lady make his story quite sad.
Well, in the movie 'Mud', Matthew McConaughey plays a character named Mud. His character has a rather sad backstory. He's a fugitive, in love with a woman he can't be with easily. He's stuck in a cycle of trying to get to her while being on the run from the law. His past actions have led him to this point where he's constantly in danger and separated from the one he loves.