Spine's always looking for ways to get under Ribcage's skin. Almost like it's a game for him. Just to see how far he can push her, see how many times he can get her angry, just for the heck of it. No one's really sure why the two are always at each others throat, they just are x'D ever since they met they've been biting each other constantly.

And here Spine is leaving his scent in one of Ribcage's areas she likes to hang out. Because he knows she hates him doing that lol For one she hates his scent, and two she's sick and tired of him somehow getting into her territories! So rude! The little punk ass bitch!

Also yes Spine's unrine is black and oil-like, the same can be said for his drool and other fluids. He does not however produce waste. Just piss haha He's a little bit older in this scene compared to the previous art I did of him, which is why his wings are gone (they are removed by the doctor).