Prisoner 818 is a minor character in Sense8 season one, played by Hey Ryoung Koo.
When Sun is at sewing duty, learning from Soo-Jin, Prisoner 818 comes and switches Soo-Jin's finished garments for her own undone ones, mocking Soo-Jin as she leaves for outside privilege. Shocked, Sun asks if this happens often, which Soo-Jin pitifully confirms.
At another day of sewing duty, Lina warns Soo-Jin when 818 is coming. Sun asks Soo-Jin why 818 pick her, which Soo-Jin explains to be because she works fast. Soo-Jin adds that she once tried to work slower, which backfired.
Deciding that Soo-Jin deserves to enjoy some painting at outside privilege, Sun trips 818, who curses "Bitch!" as she falls. The noise draws the attention of the guard, who scolds 818 for not finishing her duty. As she walks back to her seat, 818 angrily glares at Sun, who defiantly stares back. Sun explains Soo-Jin the "second mover advantage", that she learned from her father, and tells her to enjoy outside while 818 will sew.
When Sun is done sewing herself, she joins Soo-Jin painting the mural outside, and makes a picture of when her mother took her to the Spring Festival and had ice cream, which is promptly ruined as 818 splashes a can of red paint at it. She then teases Sun about the "accident", and proceeds to accuse Sun of believing to be better than the rest of them. As she remarks on Sun having "a smart mouth", Sun tries to reason that it would be stupid to start a fight for no good reason. 818 is too annoyed by her wit to care and attacks.
Sun dodges her punches and manages to seize her, asking to stop the fight as she doesn't want to hurt her. But 818's peers join along, forcing Sun to use her skills to protect herself. 818 pulls out a blade and manages to slash Sun's abdomen. As Sun gets to seize 818 again, a group of guards come and put a stop to it, taking them both out.