"My dad always said... "if you need to know a city, ask the rats.""

  • Mercury Black

"Let's just keep this between us friends."

  • Mercury, revealing his true colors to Ruby as she fails to call for help.

Mercury Black is a major antagonist in the American web cartoon series RWBY. He is one of Cinder Fall's two right-hands alongside his partner, Emerald Sustrai.

In Volume 2, he was voiced by J.J. Castillo. He is currently voiced by Yuri Lowenthal, who also voiced Sasuke Uchiha and That Man.



Mercury lived in the mountains with his father, Marcus Black, who was an assassin and heavy drinker that would abuse and beat him. One night, he fought against his father and killed him.

Cinder Fall and Emerald Sustrai saw their fight from afar and were hoping to recruit his father for their cause. However, due to Marcus' death, Cinder asked Mercury if he took after his father. He joined Cinder's faction and has been traveling with them since.

Volume 2

In "Best Day Ever", Mercury and Emerald arrive at a book store owned by Tukson and Emerald asks him if he has certain books. Meanwhile, Mercury continues to pick up books and slams them loudly during Emerald's questioning before asking if he has any comics. When Emerald begins to reveal why they are really there, Mercury dims the windows of the shop and kills Tukson when he tries to attack them.

Mercury returns to Roman Torchwick's hideout with Emerald and informs Roman that they were out "cleaning up his problems". Cinder soon arrives and Mercury confirms that they had indeed killed Tukson before he had the chance to flee. When Roman tries to explain to Cinder why he hadn't done the job himself yet because of how busy he is stealing Dust, Mercury compares him to any punk with a gun and ski mask. He then leaves the warehouse with Cinder and Emerald.

In "Welcome to Beacon", Mercury arrives at Beacon with Emerald and Cinder, posing as students from Haven Academy. The three bump into Ruby Rose, where Mercury informs her that they got turned around looking for their building. Ruby then tells them the direction of their building and the trio continue on their way as Ruby welcomes them to Beacon Academy.

In "Extracurricular", Mercury is seen watching Pyrrha Nikos fight with Team CRDL in a class based training fight. Once Pyrrha finishes with the former, Mercury challenges her to a sparring match. Glynda Goodwitch briefly protests this, but Pyrrha gives her approval and the match begins.

The fight is tense, with both parties probing for weaknesses and studying their opponent's skills. Pyrrha briefly uses her Semblance of polarity to manipulate Mercury's boots, throwing him off-balance. Midway through the brief but intense match, Mercury abruptly forfeits, stating that Pyrrha, a world-renowned fighter, is completely out of his league. After the match, he briefly converses with Emerald and enthuses about how much fun he finds learning. He is later seen discussing Pyrrha's Semblance and skills with Emerald and Cinder in their dorm rooms, conveying his findings from their match.

In "Burning the Candle", Mercury enters the ballroom with Emerald and is welcomed by Yang Xiao Long, followed by his answer that both of them wouldn't miss the dance for the world.

In "Dance Dance Infiltration", Mercury is seen dancing with Emerald, while talking to Cinder through a headpiece at certain points throughout the dance. After Cinder arrives at the dance, having successfully completed her mission, Mercury dances with her and asks how her night was, to which she responds that it was much more exciting than expected.

In "Breach", Mercury appears alongside Emerald and Cinder during the Grimm attack on Vale, who silently nods to the two to attack and help in taking out the Grimm attacking humans. Shortly after the fight, Mercury, Emerald and Cinder are overlooking the city of Vale from a rooftop. When Cinder remarks on the day being successful, Mercury adds that with them having lost so much Faunus in the caves, the White Fang won't listen to them anymore. At that moment, Adam Taurus appears and reassures them that they will listen to him.

Volume 3

In "Round One", Mercury is first seen observing different boots at a stand in the fairgrounds. After Emerald is done conversing with Team RWBY, she returns to Mercury, and he asks if she got the information. She tells him Weiss and Yang will be fighting in the second round. He is later seen eating a big bowl of popcorn while spectating the match between Team JNPR and Team BRNZ along with Emerald and Cinder.

In "It's Brawl in the Family", Mercury witnesses the fight between Qrow Branwen and Winter Schnee. As soon as he recognizes Qrow, he becomes worried and runs off to report to Cinder.

In "Lessons Learned", Mercury and Emerald are faced off with Coco Adel and Yatsuhashi Daichi of Team CFVY in the double match due to Cinder rigging the match up. He and Emerald easily win the match.

In "Never Miss a Beat", Mercury is later seen doing push-ups in the Beacon dorms with Emerald and Cinder nearby as the latter looks through James Ironwood's files and finds information on Penny Polendina.

In "Fall", Mercury is elected to represent his faction in the finals round of the tournament, facing off against Yang in the first match. While the two are appear to be evenly matched in the beginning, Mercury unleashed a storm of rounds at her. Just as he walks away, brushing his clothes off in confidence of his "victory", Yang rebounds from his attack and proceeds to unleash a beatdown that costs him the match.

However, he is involved in an elaborate ruse where Yang is tricked by Emerald into seeing Mercury attack her despite his lack of Aura. This causes Yang to attack him in self-defense and "fracture" his leg; allowing him to frame Yang for seemingly assaulting a non-combative opponent. Emerald rushes to his side as he clutches his leg and cries out in pain. However, his legs are prosthetic, unbeknownst to the others present, and he can repair them himself.

In "Beginning of the End", Mercury is evacuated by Cinder and Neopolitan in an Air Bus to their secret warehouse where he hides away so that nobody knows his leg is fine. Cinder's plan carries on with him in hiding.

In "Destiny", Ruby finds Mercury in the stadium with fully healed legs. He notes that the next matchup, Pyrrha versus Penny, will be chaotic due to Pyrrha's polarity and Penny's metal body. Mercury then assumes a fighting stance, preparing to attack an unarmed Ruby.

In "PvP", Ruby attempts to both speed past Mercury and call for help via her Scroll, to no avail, as Mercury impedes her movement, and shoots her device from her hand. Ruby eventually manages to evade and escape, but only arrives to see Penny's destruction at the hands of her opponent. Seeing the plan was successful, Mercury leaves Ruby to grieve without further harming her, going back the way he came.

In "Battle of Beacon", Mercury is seen with Cinder and Emerald, standing on a rooftop as he is filming the Grimm's attack on Beacon with a Scroll. Cinder instructs him to focus on the infected Atlesian Knight-200s, before he is interrupted by the Grimm Dragon's arrival, which Mercury also focuses on.

Volume 4

In "The Next Step", Mercury is seen present at Salem's Domain surveying its surroundings and accompanying Cinder alongside Emerald. He gets upset when Watts mocks him, but is restrained by Emerald.

In "Of Runaways and Stowaways", Mercury and Emerald watch Cinder receive "treatment" from Salem. Both he and Emerald back away in fear as a Seer comes in to report the Grimm's lack of success in finding the relic at Beacon Academy.

In "No Safe Haven", Mercury is seen watching Cinder train with Grimm and then incinerate a vision of Ruby created by Emerald.

Volume 5

In "Rest and Resolutions", Cinder arrives at the Branwen Tribe campground with Watts, Mercury and Emerald.

In "A Perfect Storm", Mercury introduces the group as people Raven should be afraid of, and upon Raven's dismissal, Cinder quiets Mercury's ensuing outburst. They tell Raven to bring Vernal as the Spring Maiden to Haven Academy to unlock its Relic's chamber. After negotiations, Mercury and the group return to a ship where they take rest.

In "The More the Merrier", Mercury then accompanies Cinder as she leads the assault of Haven and confronts Yang, demanding for an apology for his leg back at the tournament. They fight, but their battle is interrupted when Cinder impales Weiss Schnee.

In "Vault of the Spring Maiden", Mercury teams up with Emerald in stopping Yang from following Cinder into the vault, using her hallucination Semblance to create multiple clones of him. However, their advantage is cut short when Ruby rushes in to save Yang and assist her in the fight.

In "Downfall", Mercury knocks Crescent Rose out of Ruby's hands and taunts her lack of skills without it. However, he is shocked when Ruby headbutts him and proceeds to retrieve it. Mercury later attempts to stop Yang from reaching the vault and grabs her prosthetic arm, but she detaches it and makes it inside.

In "Haven's Fate", Mercury shows annoyance when Lionheart flees in terror after Blake and the authorities arrive. Eventually, Mercury is brought to his knees and realizes their side is losing the battle. When Yang returns from the vault with the Relic of Knowledge, Mercury assumes the worst for Cinder and tells Emerald they need to retreat. When Emerald overexerts her Semblance to create a massive hallucination, Mercury and Hazel grab her and take the opportunity to escape, their mission at Haven a failure.

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In "Best Day Ever", Mercury is shown to be rather care-free and jokes around when in the company of Emerald, whom he makes an effort to annoy. He seems to opt for excitement and action; he dislikes books without pictures and tells Emerald he finds the city boring. However, when it comes to matters at hand, Mercury drops this and focuses himself on the mission. His carefree attitude however may occasionally slip out during combat, such as when he taunted Ruby Rose during both their encounters once he got the advantage in their skirmish.

During battle, Mercury displays a sense of seriousness and levelheadedness. Based on his fight with Pyrrha Nikos, he appears to test and gauge his opponent before fully committing to an attack, implying he has a strategic mind. His cunning is later shown once more during his match against Coco Adel and Yatsuhashi Daichi in "Lessons Learned", where he takes advantage of the savanna biome to hide before launching a surprise attack on Coco. He also uses the geyser biome to his advantage, using it to create an opening on Yatsuhashi and defeat him.

Judging from the nonchalant way he talks about killing Tukson, Mercury appears to have no qualms about intimidating others and killing, even light-heartedly joking about it afterward with Emerald. Although subtle, he also speaks in a derogatory fashion about Tukson even after having murdered him in cold blood. This is probably due to his father's tutelage as he was most likely taught in the ways of assassinations.

He also seems to derive personal enjoyment from the pain of others. Whether this is for his own self-satisfaction or to put his opponents in an unstable state of mind to take advantage of their emotions is unknown. Examples of this are seen in "A Perfect Storm" where he attempts and fails at intimidating Raven Branwen and later in "The More the Merrier" when he condescendingly asks Yang Xiao Long and Ruby if they missed their old 'friends'. Later he tells Yang she 'owes' him an apology for his leg before turning serious for their rematch. This side of his personality is also briefly seen in the same episode, as he smirks proudly when Cinder torments Jaune Arc. However, despite his sadistic streak, he is not incapable of caring for others. He takes on a soothing tone when convincing Emerald to retreat from battle while she grieves over losing Cinder.

In "It's Brawl in the Family", he appears to show genuine concern when spotting Qrow Branwen, knowing he poses as a substantial threat to Cinder's agenda and shows total cooperation in letting her know of all the details he can gather.

"Fall" and "Beginning of the End" demonstrate his acting ability, where he plays a major role in framing Yang Xiao Long; he makes it seem she initially attacks and lands a serious injury on him, when in truth, due to his prosthetic legs, the injury is not as grave as everyone else is led to believe. He is also very compliant with Cinder's orders, allowing himself to remain hidden for the immediate future so as to not jeopardize the plan.

Despite his usual carefree demeanor, in "The Next Step", it is shown that Mercury does not take insults or disrespect well, responding to Watts' insults with an eagerness to attack him until Emerald stops him. This is further shown in "A Perfect Storm", when Raven Branwen rebuffs his attempt at intimidating her. He is usually outspoken, but when he is with Salem's group, he refrains from speaking.

Powers and Abilities

Fighting Style

Going off of his fight with Pyrrha in "Extracurricular", Mercury is shown to be a very acrobatic and agile fighter who relies on quickly overpowering his opponent with complex kicks that imply a near-mastery of martial arts that resemble Tae-Kwon-Do. He's also capable of a break-dancing style, similar to Capoeira and make use of Muay Thai as well as shown in the same fight. His experience and skill with his leg-based fighting style is aggressive and effective enough to drive even a fighter of high caliber and great combat experience like Pyrrha Nikos, considered to be the strongest first-year student at Beacon Academy, into a defensive position.

Despite his focus on kicks, Mercury also uses his hands to grapple, block or redirect enemy attacks. In his fight with Coco and Yatsuhashi, he grabs them both and twisted them into an easier position for his kicks and even stretches out Coco's arm, allowing him to kick her in the head. During his battle with Yang, he shows deft skill by using his arms to weather Yang's skilled barrage of punches. His skill in utilizing his arms is shown in the same fight as he occasionally punches at Yang before following suit with a barrage of kicks.

Mercury is also known to be observant, tactical and analytical; he notices and deduces the capabilities and limits of Pyrrha's Polarity Semblance after she uses it once during their brief fight. He demonstrates his observational skills once more when he tracks down and counters Ruby Rose's movements during her Semblance, an ability none of Team JNPRcan stop during their brief fight against Team RWBY in "Best Day Ever".

Mercury reveals the impressive extent of skill in the doubles round of the Vytal Festival, dominating both Coco and Yatsuhashi single-handed with his impressive feats of speed and strength, being capable of evading Coco's rapid and dense barrage of bullets and swiftly counterattacking from the air.

Due to his fighting style, Mercury relies on his swift and quick reflexes to counter and block his opponent's attacks as first demonstrated during his fight with Yatsuhashi. He uses certain kicks to alter the course of Yatsuhashi's sword strikes or block them altogether with his greaves. He shows quick reflexes again when he evades Yang by altering the course of her punches, using his footwork to raise her fists and kick underneath or around her attacks.


Mercury's weapon of choice is a set of boots equipped with a firing mechanism built into them, similar to Ember Celica.

Similar to Yang's usage of her Ember Celica, Mercury is capable of firing explosive rounds from his boots whenever he kicks for moderate to long-range combat. Most of the time he's seen firing his boots are usually mid-handspring, also known as a kip/kick-up or when maneuvering his body in a manner similar to break-dancing, more specifically; "Thomas flairs" and "airflares", and is able to fluently translate from his aggressive Tae-Kwon-Do-like kicking style strikes to this Capoeira style. He is also seen using it in a more traditional manner with frontal or side kicks.

Mercury can also control the rounds through Dust use. During his tournament fight, he gathered multiple rounds that spun around him in a manner similar to that of a cyclone surrounding him before the rounds were later unleashed in a devastating flurry. He also possesses, at the very least, capable marksmanship skills, being able to fire his Dust rounds efficiently despite the barrels being located near the soles of his boots, as shown when he fired a round at Yang before using his cyclone technique during their fight and when he shot Ruby's Scroll out of her hands during their confrontation.

He can also use the boots to jump in midair by bringing his legs together and firing his boots simultaneously, boosting him forward and allowing him to achieve temporary flight. This is likely a reference to the Roman god Mercury, known for his speed and ability to fly with his winged sandals.

Prosthetic Legs

Mercury has a pair of robotic legs, which he acquired at some currently unknown point in time. His prosthetics make up most of his leg, including a portion of his thigh and everything below the knee. He usually keeps them concealed under his pants. These robotic legs appear to give him enhanced performance in battle, such as being able to withstand blasts of fire without taking damage. He is also able to very easily repair "injuries" to his legs that would otherwise put a normal human out of commission or require medical attention.

His prosthetics are also quite durable, being able to withstand significant attacks that would otherwise severely reduce Mercury's Aura. His prosthetic limbs have so far protected Mercury against a nearly point-blank firestorm, a storm of frozen leaves and a direct point-blank blast from one of Yang's Ember Celica's shells. He used his legs to block a massive strike from Yatsuhashi's sword that was powerful enough to cause the geyser field biome they were in to erupt; he did this while lying on his back where he had no leverage at all, and he took little damage to his Aura.

His kick-based fighting style, as well as his choice of weapon, are likely intended to take advantage of his prosthetic legs. His prosthetic limbs are capable of firing blasts of air, which he makes great use of in combat.


"Ooh, Emerald! Master thief! Please don't take my money! I barely have enough to get by!"

  • Mercury, mocking Emerald Sustrai's confidence in her pick-pocketing.

"It's false advertising!"

  • Mercury, regarding Tukson's store catchphrase.

"You're an inspiration to every punk with a gun and a ski mask."

  • Mercury, mocking Roman Torckwick's work.

"Learning is SO MUCH fun."

  • Mercury, to Emerald.

"I HATE waiting."

  • Mercury, after being told to stay put by Cinder.

"Wouldn't miss it for the world."

  • Mercury, to Yang, about the Beacon Dance.

"I guess the general's had enough fun for one night. Should we intervene?"

  • Mercury, to Cinder Fall.

"So, how are the new friends?"

  • Mercury to Emerald about Team RWBY.

"There's not going to be a next time, Blondie!"

  • Mercury to Yang in her hallucination.

"Why'd she do that? Why'd she attack me?!"

  • Mercury, after Yang attacks him.

"Oh doc, tell me, will I ever walk again? "

  • Mercury, joking with Emerald.

"Oh, I'm getting all of it."

  • Mercury to Cinder, as he records the downfall of Beacon.

"We're the guys you should be afraid of."

  • Mercury, to Raven.

"C’mon guys, is that any way to greet your old friends? "

  • Mercury, to everyone.

"Hey there, blondie. I’m thinking you owe me an apology for my leg, don’t ya think?"

  • Mercury, to Yang.

"You’ve gotta be kidding me…"

  • Mercury, as Leonardo flees the battle.




  • Mercury alludes to the Roman god Mercury, whose Greek equivalent is Hermes.
    • Mercury's symbol, a winged boot, as well as his weapons, may be an allusion to the winged sandals of the mythological Mercury.
  • His colors are black, gray, and silver, likely to give off the tones of the element mercury.
  • Both Mercury and Emerald lacked 3D models in Volume One, using 2D still image sprites instead.
  • Mercury's last name, Black, was originally suggested by his previous voice actor J.J. Castillo.
  • Mercury's appearance, his facial features in particular, is similar to that of Sasuke Uchiha. They also share the same English voice actor, Yuri Lowenthal.
  • In the Japanese dub, Mercury is voiced by Hikaru Midorikawa, who also voiced Vidaldus Taka and Baldren Gassenral.

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