Dr Frederick Grant was a brilliant inventor man about sciences and gadgets but was really bad to jugde people. He made bussiness with the wrong people who stole the patents of his inventions and put him in prision. Grant spend years in prision where he met Wayne Williams, another inmate who also was purgin a wrongful conviction. They shared experiences and became friends.
After beign released from jail, Grant had trouble finding any job when Williams contacted him and proposed a deal: he will pose as a millionare with Wayne as his bodyguard and also will desing the gadgets and tools than Williams would need in his crusade against crime as Batman.