So I want to make Conner from Detroit become Human, question is what species and color would you guys recommend for him?

I'd recommend Arid Aeanoid. o.o I'm using this pet/color combo for my Kaname Kuran - pure blooded vampire from Vampire Knight manga/anime, because the colors are the closest to Kaname's school outfit (white), and this pet seems blood-hungry... also the overall look, seems closest to that of a human in a weird kind of way - there's a (big) head, 2 leaves that act as hands, a tall (and more or less) up straight body (the stem, because this pet is a plant after all o.o) and then the legs represented by the roots... You could choose any other basic color, depending on the clothes Conner from Detroit wears. (i'm sorry, i don't know who that is, if he's a famous person). o.o i have a big imagination i guess, if my explanation is weird XD

The one idea that stood out to me was the Steamwork Chai.

For some reason, with the pose and everything, it just looks like such a human expression, while still be a "robot."

On the other hand, depending on how you played, there's the Glacier Cadogre, who's really cool and distanced like Connor can be.

my first instinct is to suggest the experiment , though i don't know if that's too on-the-nose. or maybe an arid cadogre with the pink bits changed to cyan? but i suppose it depends on what aspect of connor you want the pet to represent.