First of all welcome to Yorkie Talk. I wanted to bump this thread up for you and I might have a partial answer. I think it is normal for a puppy to be biting fingers (even if it just started). Just keep replacing with a toy and praising. Since your puppy is obviously scared of your stepson maybe there has to be a rule like no touching unless an adult is holding Dexter. I know easier said then done but one wrong move could seriously injure him. Congratulations on your new puppy!
