Why?
Looking at their father who seemed to be in immense pain, Maxine and Ethan shouted at the top of their lungs and charged at Arnold, ready to kill him.
But, the Ethan and Maxine of this world were pitifully weak. They couldn't even lay a punch at Arnold as he dodged all of them and punched them down instead.
Maybe if it was the Ethan and Maxine of his world, they could have probably defeated him. With some effort, sure, but they'd have defeated him.
But for the Ethan and Maxine of this world who were so weak, they can only defeat him in their dreams.
He opened his mouth to ask the three men laying on the ground why they were so angry at him and so afraid of him. He got the basic gist of it from his father's shouts that he had killed his mother, but wanted to know more of what happened.