All of the character meals are ALWAYS random. Nobody will ever have a chance to know what characters are there until it has begun. The exception is the character for whom the meal is named. Goofy at DLH, Minnie in the park, Chip and Dale for Storytellers, Ariel at the Grotto, etc. I think it depends in part on what cast members come in and what costumes they fit. We've seen Rafiki at Minnies, and others have seen him at Storytellers. We saw Brer Bear at Storytellers but Brer Fox at Minnies. There's a lot of flip-flopping.
If you just missed a character you wanted, you can tell the handler and they will be sure that character comes back for you.