Mercury Black

Mercury Black is an associate of Cinder and a possible partner of Emerald. He makes his first appearance at the end of Black and White in RWBY Volume 1

Appearance
In Mercury's first appearance in Black and White, he was shown to be a pale, well-built man with purple eyes and hair, partially slicked back while unkempt at the front. He also wears a gray and black two-tone partial-zip jacket, that covers his upper body.

Mercury's appearance did not change much in Volume 2, though his hair and eyes are now a silvery-gray. A not so noticeable change is his style of belt. In his first appearance, he appears to be wearing two belts, one crossing the other. He now wears a single notched belt with what appears to be a sash or bandana draped over it. It is unclear whether his rerebraces are attached to his jacket.

In the Volume 2 Opening, he is seen fighting with greaves similar in design to Yang's Ember Celica.

History
In the post-credits scene for Volume 1, Mercury and Emerald are seen accompanying Cinder Fall to a meeting with Roman Torchwick.

Some time later, Mercury fights Pyrrha Nikos in a tournament-style setting at Beacon Academy, while Emerald, Ruby, and other students watch from the sidelines.

Personality
Though little is shown in the way of how he interacts with others, Mercury displays a sense of seriousness and levelheadedness. Based on his fight with Pyrrha, he appears to test and gauge his opponent before fully committing to an attack, implying that he has a strategic mind.

Also, something noticeable during the sneak peek is Mercury's lack of using the firing mechanism on his greaves. This could imply that he is a very confident and proficient fighter who feels no need to use his full range of abilities, even in a fight against a strong opponent like Pyrrha.

Skills and Abilties
Based on his sneak-peek fight with Pyrrha, 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 was even able to outmaneuver and disarm Pyrrha, although the entirety of the match was not shown.

He also wields a set of greaves that have a firing mechanism built into them similar to Ember Celica. He is shown using them briefly in the Volume 2 Opening, which shows that they operate the same way Ember Celica does.

Trivia

 * Despite his hair and eye color being purple in Black and White, his silhouette and the official poster for Volume 2 show his hair as silvery-gray. His initial appearance is in a very dark setting, which may be why his hair and eyes seem to be purple.
 * Mercury seems to be based off the Roman mythological figure of the same name.