Missy has been lobbing insults and unkind words non-stop. This can really, really put James in a tither. He hasn't ever been able to walk away or let it go. He cries. I coach him often through the day. I remind him that she's angry at the world and nothing can make her happy and every reaction from him is another victory for her ugly darts.
Isaac, on the other hand, does not take any of it personally. He's grown up with older brothers. I dare say they have teased and kidded each other around enough for him to know that words are only words. So when she screamed at him that he was a stupid idiot he just turned and smiled and said, "Thank you." And kept on what he was doing.
James watched this a few times. They discussed it. And then we all discussed it. I added a few other lines for him to add like, "You are such a sweet, kind sister! I love you!" If said in sarcasm it could mean more trouble, but if said kindly it could be helpful. It's not exactly truth. . . It's what we want for her.
He tried it out and the results were as expected. She scowled and walked off. I don't know if he can remember when it makes him so mad to be screamed at. He knows all about it. He's done it himself a million times, but funny it bothers him when it comes from the other direction.