How to straighten out a difficult teenager?

My son is very strong-willed, and is very hard on his stepmother. She tries to control him, but it doesn't work. The relationship between then has gotten steadily worse over the last 7 years. It seems like peace in my house is impossible to achieve. How can I convince him to behave in a way which she will be satisfied with. He's 13 years old. He does most of what I ask of him, but his problem is with her. Can he be helped? Can she?