Anyone familiar with the book series would recognize it without, and
apostrophes in given names can be a nuisance when it comes to filling out school forms, the department of records, etc. Computer-generated forms often drop the apostrophe or sometimes end the name at the apostrophe, or inform you that you are not allowed to do punctuation, and it's annoying to have the forms world get it wrong all the time. That said, keep it if it matters.
Like both names.