I think a basilisk or warp stalker of some sort would probably fit well. the color and level would depend on personal taste. a few other pets I think would fit well reguardless of color are core hounds, dragon hawks and any color rune dog.
Also if you are interested in gem pets

for lvl 73, or for a low level the ghostly version can be obtained at 25, as well as the rare blue one.

and at 48 there is a personal favorite of mine, olm the wise.

you could grab this guy at 48.

as well as this ghostly white bird at 41.

(there is also a blue version at 66)
lost of lower level cat options. the lvl 47 mage experiment gone wrong
the red-eyed shiny skinned lvl 28 oddity

or my favorite and one you don't see much anymore. the lvl 20 ghost saber.

blue-eyed white chimera

I can think of lots more but I think I will stop before this turns to spam.

There are tons of wasps, snakes, nether rays and moths that could fit well too depending on what colors you like.