So, if a book/comic/etc. is being turned into a movie/TV/etc., some changes have to be made to make the movie/TV/etc. any good.

If your fandom is being adapted and you have a favorite character, what are the traits that have to remain or the adaption will fail for you? What changes could you live with or do you think couldn't be translated well?

(For instance, I liked Elrond for his kindness/compassion and Faramir because he wasn't tempted, so the movies failed those two characters. Etc.)