I couldn't find any information on "The Devil Wears Prada 2" with a character named Callum Harper.
However, I believe you might be referring to the original movie "The Devil Wears Prada" (2006), which is based on the bestselling novel by Lauren Weisberger. The movie features Emily Charlton, played by Emily Blunt, and Nigel, played by Stanley Tucci, as key supporting characters.
Another possibility is that you might be referring to the Canadian metalcore band "The Devil Wears Prada," founded by Jeremy DePoyster and Mike Hranica. The band has undergone some lineup changes over the years and has had several members, including Callum Green (guitarist) and Jeremy DePoyster (vocalist), but I couldn't find any information on a member named Callum Harper.
