Alright so more story-related stuff than production-related stuff This is River! She was probably the character Viv drew the most aside from the main 3. Originally she was an owl kinda like Maggie and Quincy, but she was changed to be a deer later on.

I alluded to this earlier, but Timber herself underwent a few resesigns after the short was released. I really love how her design ended up in the end, just a massive improvement imo