I have a theory, Sophie and keefe are the same age.
When Sophie comes to the lost cities she enters level two, but in Neverseen we learn she was actually supposed to be a level three.
When we think of keefe most of the time we forget that he skipped a level and therefore is a year younger than Fitz so if we think about it, Fitz and keefe were level for in book one and Sophie was level two but should have been level three, and keefe was supposed to be a level according to age, that makes them the same age which is 13-14 for that year so there both the closest in age out of the whole crew. In regards to whose closest in age to sophie.
