Lovers & Fighters

Charlie has discovered how to hit things: Bo, Polly, Kelsey, and Madeline. And poor Maddie just takes it and cries. Then she proceeds to crawl in my lap and cuddle with me. Madeline is definitely my lover, while Charlie is the fighter. We try to tell him no and put him in his crib when he has bad behavior, but we don't know what else to do. Any suggestions? Otherwise I'm afraid he'll be the class bully (with all the boogers!) !