In my opinion, M&M chose to ran away because he felt like he didn’t fit in, that he was too different. He tried making a point about how violence was not the right solution, but no one would actually care about what he would say. Also, he is not happy at home and he’d rather be anywhere else than be in the same house as his dad. Cathy even described him as being someone who is easily influenced and could easily be addicted by hard drugs. He is known for being someone who isn’t stable since the beginning of the book, and by running away, he will actually find peace on what everybody say about him. He couldn’t take any of what people use to tell him anymore, so in my opinion, he ran away partly because of that.