Agent of Mother Brain
Full Name: Atropos
Symbolic Identity: Atropos
Atropos, the feminine robot who is of Robo's R series sent as an assassin of Mother Brain to annihilate Robo, was named after and is similar to Atropos, a Greek Fate who cuts the threads of life.
Atropos, in Greek mythology, was one of three Fates. The Fates were female entities who spun, determined, and cut the "threads of life" that supposedly determined the nature of a mortal's life. Atropos was the latter of the three, who cut the thread of life, thus determining just where and when each mortal would die. Her murderous nature is signified in Chrono Trigger, with Atropos being the robot who is sent to kill Robo.
The Fates were servants of Zeus, the chief god of Greek mythology. This is similar to Atropos being a servant of Mother Brain (similar to Zeus in more than one way).
War (CiJoWa@cs.com) has suggested an interesting interpretation of Atropos's actions after her defeat. She gives Robo a ribbon which greatly enhances his abilities. Considering that Atropos is a Fate who deals with the threads of life, perhaps the ribbon can be seen as a thread of life that extends Robo's life rather than cuts it short. Sort of like she's giving Robo her thread of life, which has just been cut by him.