Emerald is Cinder's first known recruit. Cinder happens to notice Emerald use her Semblance in order to steal, and corners her in an alley while the police are giving chase. Cinder tempts Emerald to join her by promising that she'll never go hungry again. It is also suggested in "Beginning of the End" that Cinder demonstrated a power Emerald previously believed impossible, and thus kept her in line as a subordinate.
Emerald appears to be under Cinder's direct command and obeys her orders without question. Emerald seems to have the utmost respect for Cinder and greatly values her approval, sometimes even addressing her as "ma'am" instead of by her name, and eagerly going out of her way to perform tasks for her.
In "Best Day Ever," she enthusiastically greets Cinder when she appears. Conversely, after being rebuked for acting impulsively, Emerald looked saddened and said that she wouldn't do anything without her orders again.
"Beginning of the End" reveals that part of Emerald's loyalty to Cinder is due to being saved by her from living on the streets. Whatever affection toward Cinder she has in connection to this is not equally returned, as Cinder can be heard striking Emerald and reminding her to know her place when Emerald speaks out against recruiting Mercury Black.
After the Fall of Beacon, in "The Next Step", Emerald appears to worry about Cinder deeply. Due to Cinder's injuries causing her to be unable to speak at an audible level, Emerald ends up interpreting and relaying her speech to others.
In "The More the Merrier" Emerald reveals to Ruby her debt to Cinder and is willing to serve Salem for her master. In "Haven's Fate", Emerald breaks down in tears after realizing Cinder was defeated, causing her to scream in agony as she inadvertently activates her Semblance on everyone in her grief.
Mercury is Emerald's partner and the two share a close relationship. She appears to be mildly annoyed by Mercury's antics, but they are also shown lightheartedly joking with each other.
They take each other's side against Roman, whom they both appear to hold a great deal of derision for. Emerald and Mercury work effectively as a team, accompanying each other on missions. They also coordinate with each other in battle, often with Emerald distracting the enemy with hallucinations and Mercury following up with surprise attacks.
After Mercury's leg is seemingly broken by Yang in "Fall", Emerald rushes to his side and apparently shows concern for his injury, though this was part of the act.
In "Beginning of the End" it is revealed that Emerald initially protested Mercury's recruitment.
As one of Cinder's subordinates, Emerald works with Roman, but appears to have little respect for him. She is repulsed at the thought of him "procreating" and the two pickpocket each other in mutual slights. Unlike her playfully hostile relationship with Mercury, Emerald appears to have a genuine dislike for Roman, who even goes as far as threatening them both.
Emerald also undercuts him with Cinder by boasting of how she and Mercury handled Tukson while Roman did nothing.
Emerald and Neopolitan participated together in the Vytal Festival Tournament as a team, along with Mercury and Cinder.
While they've had little interaction, it's evident that Emerald is afraid of Salem, but is willing to accomplish Salem's goals under Cinder's direction. When interpreting for Cinder, in "The Next Step," she only speaks after Salem lets her, and nervously at that. In "Of Runaways and Stowaways", when Salem angrily orders Cinder to force out her own answer, Emerald stays silent.
In "The More the Merrier", Emerald tells Ruby that she doesn't care about Salem, but indicates that if Cinder's orders align with Salem's goals, she'll follow them.
The two first met when Ruby accidentally bumped into her while running to the library to retrieve her board game. Emerald helps the latter up after she fell. After some interaction with Cinder, Ruby then redirects Emerald, Mercury, and Cinder to their respective building.
In "Extracurricular," Emerald is seen putting on a friendly act around Ruby, smiling sweetly when she speaks to her, but scowling and rolling her eyes as soon as Ruby looks away.
In "Round One," it is revealed that Emerald has managed to forge what initially appears to be a strong friendship with Ruby and her team in the interim between the end of the second semester and the beginning of the Vytal Festival. They greet each other amiably and share a pleasant conversation, and Ruby even invites her and her team out to lunch.
However, once their backs are turned, she expresses her intense dislike for Ruby and her team to Mercury, claiming that she can't stand their constant positivity. Evidently, she only tolerates their presence due to being on a fact-finding mission from Cinder.
In "The More the Merrier", Emerald fights Ruby to prevent her from helping Jaune Arc. She easily fools Ruby with a hallucination of Cinder and later knocks her out to prevent her powers from harming Cinder. In "Haven's Fate", Emerald refuses to surrender to Ruby and her friends, as she is confident that Cinder will defeat all of them.
Like the rest of her team, Emerald has managed to fake a friendship with Yang, who appears familiar with her, even fondly addressing her by the nickname "Em." In actuality, Emerald holds Yang in low regard, referring to her as a "bimbo."
After Yang breaks Mercury's leg following their match in the finals of the Vytal Festival tournament, Emerald shoots Yang an angry glare for hurting him. Though part of the act, it is possible she was letting her true opinion of Yang show through.
In "Haven's Fate", Emerald is shocked when Yang emerges from the vault with the Relic of Knowledge.
Together with Mercury, Emerald seeks out Tukson to kill him due to his intentions to leave the White Fang and flee to Vacuo. The pair at first toy with him, with Emerald putting on a friendly façade and enquiring about his inventory of books, before they begin to intimidate and ultimately kill him.
She appears to show no remorse for him after he is killed, even joking about the matter and calling him a rat.