The Scarecrow (Gotham)'s History
Jonathan Crane is a deranged, criminally insane teenage psychopath and anarchist. He is the son of the late Gerald and Karen Crane. As a child, his mother died in a house fire, causing his father to try to stop fear until his inevitable death. Not long before this, his father injected his son with the serum he made, which overloaded Jonathan's fear response causing his mind to create a boogeyman of what he feared the most, a scarecrow, driving him insane.
He would later be transferred to Gotham Asylum for his condition, until Merton and his gang bribed the warden into releasing him so they could make Jonathan recreate his father's serum and pose as a threat to Oswald Cobblepot. However, the gang locked him in a closet with a scarecrow much to his dismay and horror until he became one with his fear, wearing the scarecrow as a costume and abandoning his birth-given name in favor of The Scarecrow. After spraying a member of the gang with fear toxin, he would return to the old asylum seeking revenge on the warden and attempting to "free" his fellow inmates until Jim Gordon would arrive and discover the serum's weakness, water.
Crane would eventually be captured again and sent to Arkham Asylum however, he would soon escape with his new allies Jerome Valeska and Jervis Tetch. This alliance later evolved into the Legion of Horribles, reinforced with Oswald Cobblepot, Mr. Freeze, Firefly and Solomon Grundy, which operated with the goal to drive Gotham City into madness according to a plan by Jerome, while the other members were promised to rule the city after its downfall. On Jerome's request, Crane therefore developed the dangerous Laughing Toxin. The Legion was ultimately dissolved after their leader Jerome Valeska died once again, whereupon Scarecrow allied with Jerome's brother Jeremiah Valeska, assisting him in driving Bruce Wayne mad, while Crane also fought Selina Kyle in order to prevent her from ruining Jeremiah's plan.
During the No Man's Land event, Crane claimed his own territory and established a gang.