Expressions.

I've drawn out some basic expressions for Rutherford along with a few different angles for his head/face, then done some simple colouring to try and work out how the lighting would work and whatnot.

A staple part of Rutherford's expressions has become the little line that shows the quirk of his upper lip. I think it gives him that snootier edge. I've tried working with how the ears can show expression too - flattened for sadness or anger, upright for excitement or laughter, a slight curl at the tips for vague interest. Drooping the nose/snout also works for portraying sadness or disappointment, while turning it up more dramatically can give either a pompous or mischievous look depending on the rest of the expression.

I'll be taking a look at how other animal characters' expressions are handled in cartoons for more potential ideas regarding my character. Using the shape of the face and ears itself seems a good way to give him more life and show his true thoughts, mostly since his eyes are very simplistically drawn and often neutral/bored-looking.