Jack Thomas "J.J." Deveraux, Jr is a fictional character from the NBC soap opera Days of Our Lives currently portrayed by Casey Moss. JJ is the second child of Jennifer Horton and Jack Deveraux . He is the brother of Abigail Deveraux. He is the grandson of Bill Horton and Laura Horton and Jo and Duke Earl Johnson. He has been in boarding school since he left Salem with his parents.