Emerald Sustrai

Emerald Sustrai is an antagonist in RWBY. She is an associate of Cinder Fall and the partner of Mercury Black.

Appearance
Emerald is a young woman with medium-brown skin and dark-red eyes. Her hair is a light, mint-green 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 strappy high-heeled pumps.

Originally, her attire consisted of an intricate white top and an olive-colored crop top, on the back of which is her personal emblem. This emblem 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 crop top 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.

Haven Uniform
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.

Flashback
In "Beginning of the End", Emerald was younger, noticeably thinner, and had her hair tied into a ponytail.

Her previous attire was a short olive-colored crop top, and she wore her signature chaps which were torn and belt. Beneath her chaps, she wore dark green pants and plain dark brown flat shoes. She also wore white half-gloves.

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 several 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 around 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 demeanor around Tukson before threatening and killing him. Another example is in "Extracurricular"; where she mostly ignores Ruby Rose until she looks directly at her when Emerald off-handedly smiles and then rolls her eyes when Ruby looks away. In the episode "Round One", she states that she dislikes Team RWBY for their cheery and positive attitude, regardless of her acting as their friend for the time being.

Emerald shows a strong sense of loyalty, specifically to Cinder, whom she is 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 judgment, 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 afterward with Mercury. However, another side of her is seen in "Battle of Beacon", where she seems to be overwhelmed and disheartened at the sheer scale of the destruction and violence taking place, calling it "almost sad". Nevertheless, Emerald continues to demonstrate loyalty to Cinder, such as in the "The Next Step" in which she speaks for Cinder, who has lost her voice.

According to Emerald, her loyalty is exclusive to Cinder, rather than to Salem, and only complies to her plans and wishes due to owing Cinder "everything".

Powers and Abilities


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 kama, the blades of which can detach and be swung from chains as kusarigama. Emerald seems to be quite adept with her weapons, demonstrating skilled swordsmanship and marksmanship, using both of her weapon forms to fend off the Grimm single-handedly in the episode "Breach". She later demonstrated the ability to ensnare opponents in her chains and reel them in, even from a great distance.

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, stealing his lighter to show him that she was a capable thief after he mocked her. As seen in her fight with Coco Adel, her stealth abilities allow her to move silently and attack from an enemy's blind spot.

Emerald is also shown to have impressive reflexes, allowing her to avoid Tukson lunging at her and dodge Coco's rapid gunfire with ease. In "The More the Merrier" her amazing reflexes are seen once again when she used her weapon to bring down Ruby from the air and slams her against the ground despite Ruby using her scythe's recoil for extra speed.

Though she hasn't engaged anyone on extended close-quarters combat, in "The More the Merrier" and "Vault of the Spring Maiden" it is shown that she's strong and skilled enough to hold Ruby at bay and even temporarily knocked her out at one point.

Semblance


Emerald's Semblance is individual mental hallucinations - the ability to modify the sensory information in a person's head while their brain is processing it. She can make one (or more) see and hear things that aren't necessarily there. In other words, instead of generating an illusion that everyone nearby can see, she causes her target to hallucinate.

This power plays a pivotal role in Cinder's plot to rig the Vytal Festival and incite anger and distrust towards Beacon Academy. After Yang Xiao Long's victory against Mercury in the singles battle, she makes Yang see a hallucination of Mercury getting up and attacking her, prompting Yang to counterattack by supposedly breaking his leg. However, in reality, Mercury hadn't attacked at all, making Yang's counter seem, to everybody watching, like an unprovoked attack in cold-blooded spite. The resulting anger, outcry, shock and distrust from the masses of watchers stirs the Grimm wandering Mountain Glenn, as the Goliaths turned their attention to Vale. She later uses it to trick Pyrrha Nikos into destroying Penny Polendina, revealing the latter to be a robot, which allows Cinder to accuse Atlas of treachery.

Before this, her power has been used to lead Amber into a trap to steal her maiden powers, where Emerald makes Amber see a crying child on the road, prompting the maiden to lower her guard; and also in her and Mercury's fight against Coco and Yatsuhashi Daichi of Team CFVY. She uses her power to hide herself and Mercury from the eyes of her opponents. After Emerald pulls Coco into the canopy section of the arena, Emerald tricks her again by making her see Yatsuhashi come up to her, seemingly victorious, only to have his defeat announced and broadcasted in the other section of the ring. Emerald then seizes the opportunity to attack a bewildered Coco and knock her out as well, winning the doubles match.

Emerald's Semblance is also the main reason Cinder first scouted her, having witnessed Emerald use her power to trick a jewel merchant, in order to steal one of his rings - the merchant just smiled at her, as she took the ring right before his eyes.

Nevertheless, her power is shown to have its limits. Whilst she seems capable of controlling a single mind, controlling any more than that seems to tax her own head severely. After playing an illusion on two medics who came to pick up Mercury so they would not see his mechanical legs, she is shown to have a considerable headache. Her illusions are also always limited in scope, making minor changes or duplicating already existing objects or people. It is shown in "Haven's Fate" that with strong emotions she is capable using it on at least nine people, but it causes her to pass out in seconds.

Another limit of her semblance is that she cannot use it while fighting. She is always seen standing still or hiding while using her power and never while fighting even when it would be better for her to do so.

Trivia

 * For information about choices the creators made for this character, see Emerald Sustrai/Behind the Scenes.
 * Emerald is a gemstone that is most often found in green colors.
 * Sustrai, capitalized, is the Basque word for "thief" while sustrai, not capitalized, means "roots" or "undercurrent".