My suggestion would be putting a little extra thought in the character's design, like for example you make a pink dog...but what is that pink dog most good at? What does it do as a job? Where does it live? Is the pink dog hyperactive? Shy? Grumpy? These little things are very important in the game's character designs. I mean, cooking cat is a mellow, friendly guy who likes cooking so he wears a chef outfit and has round shapes in his design!

That's just my take at least, hope this helps!

Wait cooking cat is a guy?

If you're going to out than into a fanfiction/fan comic/whatever, think about how they would interact with the characters and how that affects how they think about each other. Make it so that your character stands out, but still fits with the overall theme of the game.