The idea of an “old soul” in a child’s body is often framed as a slight. After all, who wants to be the most mature adult in any given situation? Hal & Harper, from writer-director Cooper Raiff, tries to dig into a family’s struggles as they blend their past, present, and hopes for the future. The series takes the old souls metaphor literally, allowing Raiff and co-star Lili Reinhart to portray…