Rick Sanchez (Gotham City Multiverse)

Unlike the Ricks we see in dimensions such as C-327, this Rick never married or had children. He is a high school dropout who relocated to Gotham City in his adult years, forging a PhD and various credentials to impress the heads of the Ace Chemical Processing Plant. He uses his position as chief engineer to cover his research into portral technology.

Dimension J-510 // J-512 (Batman: The Killing Joke, Batman: Hush Returns)

In his fifteen years working for Ace Chemical, Rick cycles through several lab assistants, driving them off with his drinking and irritability. He does make progress in his research, successfully hiding his project from the managers at Ace. He is disgruntled when the lab forces young Gotham University graduate Jack Napier on him as his latest lab assistant, but begrudgingly admits -- only to himself -- that Napier is a genius, and definitely the most intelligent assistant who's ever worked for him.

However, this does not mean he gets along better with Jack than with his other assistants. The two men often clash. Their contentious relationship comes to a head when Jack discovers Rick's formula. Before Jack can fully decipher it, Rick catches him and the two proceed to scream at each other, culminating in Rick shoving Jack's belongings off his desk and taunting him over his troubled past with his family. Infuriated, Jack quits on the spot and leaves the building.

Some months later Rick finally isolates the compound in a chemical substance; it is then that his bosses burst in. They reveal that they've been investigating Rick since Jack stormed out, and have discovered his forged credentials. Because of their embarrassment over hiring him so long in such a prestigious position, they decline to press charges, but fire him and confiscate his work. They add extra security to the plant and pour the interdimensional chemicals down into the vats below. Crushed by the loss of his life's work, Rick takes a sip of the chemical he was able to sneak undetected into his flask.

Consuming the chemical confirms his theory: ingesting it opens his mind to all the different timelines where he also sampled the chemicals. This drives him temporarily insane and the compound even changes his coloring slightly, dying his hair a faint light blue. However, by reading his notes and using all his mental stamina, he is able to bring himself back. Now, however, he has the knowledge from across different timelines to complete his portal gun. He is able to use the gun and escape his current timeline the very night Jack Napier, under the guise of Red Hood, falls into the chemical vats full of the interdimensional chemicals. The intense physical transformation combined with the bombardment of memories from across multiple timelines, and the recent loss of his pregnant wife, drives Jack completely mad, turning him into the Joker.

Dimension J-513 (Batman: Three Jokers)

The Rick in this timeline is even more ruthless and coldly analytical than his other Gotham counterparts; in fact, Jack refers to him as Mengele to his wife. Rick advances far more quickly in his work than in previous timelines, isolating the compound the day Jack finds his notes. Rick catches him but doesn't let on, instead using the opportunity to test his chemicals on Jack. He transmutes his formula into an odorless gas and leaks it out the vents and into Jack's office, and also begins to slip drops into his assistant's coffee. Rick carefully notates Jack's reactions, such as the young man going back and forth mentally between two starkly different timelines in particular: a criminal version of himself and a demented clown version.

The disorientation of these different lives pushes Jack over the edge and he quits, and then tries to stab Rick in the eye with an expansion screw key. Rick is able to knock him out with his desk clock, and take advantage of his unconscious state to inject him with a serum made of his chemicals. He believes the chemicals running through Jack's bloodstream will drive him so insane no one will believe his story. When Jack wakes up Rick doesn't press charges but dismisses him, forbidding him from coming back.

In the weeks following Jack leaving, Rick notices his bosses hovering around his lab and eying him skeptically. Believing they are on to him, Rick quickly finishes the work on his portal gun and disappears the night Batman comes to investigate him; Jack's wife Jeannie found Jack's journal about the incident and went to the police with it, a meeting Batman sat in on behind the two-way glass. However, he is distracted from his mission by the simultaneous arrival of Jack as the Red Hood. Once again there is a confrontation on the catwalk, and once again the Joker is born. Five years later, Rick takes the blueprints he's stolen from several of his counterparts across multiple timelines, and he brings them back to Dimension J-513. He returns to the chemical plant to gather some of his old equipment. Also there is the Joker, who is using the plant as his base of operations: he wants to create two Jokers with the criminal background and clown background he first witnessed after his exposure to the chemicals. He has kidnapped a dejected professional clown named Artie and dumped him in the acid to serve as the Clown Joker; now, remembering how Rick was the man responsible for setting him down his villainous path, effectively stealing his life from him, Joker lunges for Rick and pushes him into the chemicals. Like with Artie, the Joker brainwashes a transformed Rick, and dubs him the Criminal Joker.

The original Joker -- who calls himself the Comedian -- lets Criminal Joker believe he is the ringleader of the trio, and the Criminal hatches a plan to try to transform more and more men into the Joker to confuse the Bat Family. When the enterprise fails as the subjects keep dying, he then kidnaps Joe Chill to transform him into an ultimate version of the Joker. When Batman arrives to save Chill, Criminal Joker plays him a video of Chill confessing the murder of the Waynes was premeditated. Criminal Joker then tries to kill Batman, but is himself fatally shot by the Comedian Joker. Jack Napier has discarded Rick Sanchez as thoughtlessly as Rick once discarded him.