a boy and a young man travel by car in the south, they pretend to be brothers but its not true

the movie must be 8 or 10 years old, maybe less, it takes place in a southern state, a boy between 12 and 15 years old travels with a twenty-something young man, they appear to be brothers, but it’s not true, they stay in a cheap motel with the aid of a motels worker, a young female who is falling for the dangerous young man