Coulrophobia

• "X", Formerly an engineer at a chemical plant who quit his job to pursue his dream of being a stand-up comedian, only to fail miserably.

• Desperate to support his pregnant wife, Jeannie, "X" agrees to help two criminals break into the plant where "X" was formerly employed.

• During the planning for the break in Police contact "X" and informs that his wife and unborn child have died in a household accident.

• Stricken with grief, "X" attempts to back out of the plan, but the criminals strong-arm "X" into keeping his promise. 

• As soon as they enter the Chemical plant, however, they are immediately caught by security and a fatal shoot-out ensues, in which the two criminals are killed. As "X" tries to escape, he is confronted by "Y", who is investigating the disturbance.

• Terrified, "X" leaps over a rail and plummets into a vat of chemicals.

• When "X" surfaces in the nearby reservoir, "X" removes the hood and sees his reflection:The Chemicals are show to have given him a bleached chalk-white skin, ruby-red lips, and emerald green hair. 

• These events, coupled with his other misfortunes that day, drive "X" through the massive personality shift that results in the birth of the Archenemy of "Y"

Id "X and "Y"

Answer (highlight to read) : "X" - Joker "Y" - Batman