I was thinking maybe something lineless (the lines are the same colour as the pet) or with unusually coloured lines? Such as a dark pet with paler lines, like this:
Here’s one where the lineart was coloured in, so it appears to be lineless!
I think that it would be really interesting since most pets on CS have black/dark lineart! There are a few pets on CS with pale lineart but it would be nice to see more <3