(Isn't he dashing?)
Freder is the privileged son of Joh Fredersen, Master of Metropolis. His life is nothing but frivolous fun and romantic games until he briefly meets Maria, a worker's daughter. He follows her under the city, where he discovers how the workers are treated in Metropolis. Outraged, he aspires to become the Mediator between the Hands that Build and the Minds that Plan.
He also has a tendency to
hallucinate, and through his eyes
we see Metropolis in visual allegory.
Maria is the "daughter of some worker" who, in an attempt to show the children of the workers the life of the rich, inadvertently attracts Freder's attention. Meanwhile, as a spiritual leader in the Catacomb Meetings, she diffuses revolutionary tendencies and preaches patience for the coming of a Mediator who will promote understanding between the classes.
Maria's purity is often contrasted with the lecherous nature of Rotwang's Robot.
To replace his lost Hel, Rotwang the mad scientist built an evil robot. Under Joh Fredersen's orders, Rotwang gave the robot Maria's likeness to influence the workers. This may not have been a great idea, because the robot was uncontrollable and its only desires were for chaos and destruction.
Seizing control of the workers, the robot soon brings on a revolutionary riot,
destroying the engine of Metropolis and
flooding the workers' own city.
Formerly Fredersen's friend, Rotwang became a reclusive scientist when he lost a bitter rivalry over Hel, Freder's mother. Since then, he has lived in a spooky little house in the middle of the city, untouched by time, developing all sorts of gadgets the likes of which Man was Never Meant to Know.
He also has a nifty back door into the Catacombs.
Joh Fredersen is the living mind of the city; all major decisions are made through his office in a swarm of blinking lights and a stream of output tape. Before the riots, he had as little use for ineffectual staff as he had for his son's protests of the worker's squalid conditions.
But behind his cold business attitude, he has a deep love for his son, Freder.