In chapter 5 Mercury is seen sitting in a chair with a puppet that looks like Cinder on his arm. Then cinder puppet "tells him" that he's her favorite henchmen and question why she even keep the others around. She then proceeds to diss Emerald, Roman and Neo, with Mercury agreeing. She then tells him he makes her feel all "girly" to which he also agrees. Emerald, Neo and Roman are then shown standing behind him glaring while he casually continues dissing them to cinder puppet.
She then "confesses" to him that she wishes they could run away and start a family together. He tells her he's always known and proceeds to "kiss" her. The real Cinder then suddenly appears and snaps him out of his daydream by setting Cinder puppet on fire. She then threatens to barbeque Mercury if he ever does something that creepy ever again. The others then proceed to leave with Roman saying he almost feels sorry for Mercury. Emerald then says that's probably the closest thing he'll ever get to having a "real" girlfriend.
Mercury then proceeds to take out another Cinder puppet from behind him. "She" then asks him where her twin sister is to which Mercury starts tearing up. In "Nefarious Dreams", she is seen "sleeping" next to Mercury underneath his pillow, while he's asleep. In the episode where everyone goes on vaccation Cinder puppet is shown sticking out of Mercury's suitcase. In Cinder Who, while Ruby is guessing what rhymes with Fall at one point she says Cinder doll and the scene pans to Mercury with Cinder puppet making Emerald laugh.
This ship is semi-popular within the RWBY Chibi fandom, with most people treating it as a joke ship. Some people have even jokingly said it's the only "canon" ship in RWBY Chibi. There have been many memes based around these two as well. Some people have even written an au webcomic for them. It has a fanpage dedicated to them on Tumblr.
- Mercury only has feelings for Cinder in RWBY Chibi. In the actual RWBY series he feels quite the opposite about her and vice versa.