There is fic, and some of it is quite good! I'll have to see what I can track down and post some recs--I've read some that I thought were delightful, but I don't remember if they were on Tumblr or AO3 or somewhere else entirely.

Can I merge Mariel of Redwall and The Bellmaker as one favorite? ;) Mariel was my absolute favorite character from the moment I got my hands on The Bellmaker (our library didn't have them all, so I read them out of order). I loved Pearls of Lutra, too--if I ever write fic about a Redwall character, it'll probably be Grath Longfletch.