Aggressive rouen duck?

I have 3 ducks , a female pekin, make runner, and male rouen, and they are about a year old. A couple months ago, the rouen had all of a sudden became aggressive with me. He doesn't let me walk around the yard, he keeps biting my feet. he also hate my hands, and we I put things down for them he lunges at my hands. If he gets ahold of my hands he pulls the skin back and it hurts!!! I don't know what is causing this. And he is not aggressive to the other two. What should I do? The other 2 ducks don't care what I do.