Emerald Sustrai

Emerald Sustrai is an associate of Cinder Fall and a partner of Mercury Black.

Appearance
Emerald is a thin female with medium-brown skin and dark-red eyes. Her hair is a light, mint-green cut with a straight fringe and bangs, as well as two long locks on each side, in the back. She wears two bronze-colored rings on her middle fingers as well as a pair of high-heeled shoes.

Originally, her attire consisted of an intricate, exotic-looking white top and olive undershirt, on the back of which is her personal symbol. This symbol is in the shape of a cut gem, most likely referring to her name. This was intended to be accompanied by white shorts, decorated with what appears to be a gold coin-plated belt, with four gold chains draping around her back from two of the coins and what seems to be a green loincloth.

She also wore a gold, three-ring armband on her left arm and a string of gold beads near the same wrist. As of Volume 2, her outfit has changed somewhat. Her top has thinned, her undershirt is now shallow-cut, and her armband and beads no longer seem to be made from gold.

She now also wears white pants and brown chaps that end at her calves and an overlong belt, twice-wrapped, where she keeps her weapons as well as a single pouch. Her hair is also noticeably fuller and longer and her irises are wider.

Later, she is also seen wearing the Haven Academy uniform, a more conservative dark gray outfit with a long-sleeved collared top and white armband.

Personality
Emerald initially appears to be affable and disarmingly friendly, however, this belies a darker side of her character. On the whole, she seems to be genuinely outgoing and quick-witted, if a little short-fused. She can also act a little childish or petty, such as when she stuck her tongue out at Roman Torchwick after she stole his lighter to mock him.

In "Best Day Ever," when she talks to Tukson about books, she seems to be knowledgeable about books and enjoys reading, as she lists off many titles. She also likes Vale, complimenting the city for its "tall buildings and diverse culture."

She has a tendency to maintain a pretense of friendliness amongst people in order to gain their trust. This is shown on multiple occasions in "Best Day Ever," where she pretends to be friendly to the Shopkeep in order to catch him off guard and steal his wallet. Later in the same episode, she puts on a friendly act around Tukson before threatening and killing him. Another example is in "Extracurricular," where she mostly ignores Ruby until she looks directly at her, to which Emerald off-handedly smiles and subsequently rolls her eyes when Ruby looks away.

Emerald shows a strong sense of loyalty, specifically to Cinder, whom she appears incredibly eager to please. Accordingly, she is willing to take the initiative to impress her, such as tracking down Tukson and killing him. When Cinder rebukes her for killing Tukson, she defers to Cinder's judgement, quickly apologizing.

Judging from the nonchalant way she talked about killing Tukson, she appears to have no qualms about killing, even lightheartedly joking about it afterwards with Mercury.

Abilities and Powers
Emerald's weapons can take two main forms - primarily, they act as a pair of dual-wielded pistols, but they can also be converted into a pair of short scythes or kamas, which also have chains attached for them. Although she was only seen using them once (not counting her appearance in the opening), Emerald seems to be quite adept with her weapons, demonstrating skilled swordsmanship and marksmanship, using both of her weapon forms to fend off Grimm single-handedly in the episode "Breach."

Emerald is stated by Mercury to be a master thief, and she has proven that she is adept at pickpocketing, with one victim being Roman Torchwick, stealing his lighter to show him that she was a capable thief after he mocked her.

Emerald is also shown to have impressive reflexes, being able to avoid Tukson lunging at her.

Trivia

 * Both Emerald and Mercury lacked 3D models in Volume 1, and were simply shown as 2D image sprites instead.
 * In the episode "Best Day Ever," Emerald is established by her actions and Mercury's own words as a "master thief." Later, Roman refers to Emerald as a "street rat," a term used to describe the title character of Aladdin. It could suggest the basis of Emerald's character, as well as her name making allusion to the phrase "diamond in the rough", which is spoken in the Disney adaptation of the tale.
 * Sustrai (capitalized) is the Basque word for "thief" while sustrai (not capitalized) means "roots" or "undercurrent." It may also come from the Spanish word "sustraer" which means "to steal" or "rob."
 * Emerald's appearance greatly resembles that of Cleopatra, who was supposedly cursed by an emerald.
 * Unlike Cinder and Mercury, Emerald's eyes are more circular in shape. In practice, this style of eyes is normally reserved for positive/innocent characters.