Dexter told Delilah that she should stop being afraid of her two visiting cousins from England. Just because there are two visitors in the house, doesn't mean she has to run and hide everytime they enter the room. In fact, Dexter told her that he doesn't even mind sharing his chair with Josh and taking a short cat nap with him.
Delilah still is not convinced. She thinks it is safest to stay well out of reach of these two visitors except at mealtimes.