As a student at UCLA in film writing something an instructor said stuck with me, "complex characters, simple plot." To achieve this takes some hacking ... lots of sketching, notes, observing in ways I normally do not.
All of that is well and good, but let's add a couple of twists. It's an animal. An animal not well understood or socially accepted as a house pet. A rabbit. Rabbits who live on farms, in the wild, in Beatrice Potter's books. And a rabbit who is like a dog and cat in one. Who will not accept a mate because he's decided on the human equivalent, who sleeps in the bed and is perfectly polite about toilet habits. And much more.
To do this would take daily work for awhile. Lots of content that could be trashed, an MD notebook in storyboard form and the motivation of a community doing 100 drawings. A hundred drawings is about right.
At the moment I've created 60 with 40 to go and it's been a learning process for sure. It's challenging not to take it to the fantasy realm - high concept and fictional. The way I've handled that is to carve away at a characteristic with many scenes until I capture a real quality about his character.