Emerald Sustrai/Affiliation

Cinder Fall
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, eagerly going out of her way to perform tasks for her.

In "Best Day Ever," she enthusiastically greets cinder when she appears, and her face appears to light up. Conversely, after being rebuked for acting impulsively, Emerald looked saddened and said that she wouldn't do anything without her orders.

Mercury Black
Emerald is a partner of Mercury, and the two share a close relationship. She appears to be mildly annoyed by Mercury's antics, but the two are also shown lightheartedly joking with each other.

They also take each other's side against Roman, whom they both appear to hold a great deal of derision for. The pair also appear to work closely and effectively as a team, accompanying each other on missions.

Roman Torchwick
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.

Emerald also undercuts him with Cinder by boasting of how she and Mercury handled Tukson while Roman did nothing.

Ruby Rose
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, telling to Ruby to only mind where she is going. Ruby then redirects Emerlad, Mercury and Cinder to their respective building.

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.

Tukson
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 him afterwards with Mercury.